user1364: Sure, I could Google and find random software. But I rather have the opinion of users that have had hands-on with any open source video editors.
So if you've used one that you like or know of any, please let me know and state whether you've used it or just know of it (and heard good things). Thanks.
I'm looking for Windows software. But you may suggest Linux as well for other people that might stumble upon this.

user18314: Better than mearly good is AviSynth: http://avisynth.nl/index.php/Main_Page .
Basically you write a Script and then open the Script in a Player. The Script can change the input in many ways and there are many 1000's of Plugins. There are a few Forks including some 'traditional' looking Editors that use AviSynth under the hood.
After tweaking the Script precisely you simply 'copy' the Script (possibly with Ffmpeg) and render a final version.
Includes capabilities to express exactly (to the pixel and frame) what you want. Not too bad a learning curve and so many examples available. During several years of use I discovered no Bugs but apparently others found a couple that have since been fixed. Open Source and you assistance is welcome.
Often used in conjunction with VirtualDub to provide a GUI.

user95: A friend of mine liked VirtualDub quite a bit, which is free. I have not, however, used it myself.

user2459: OpenShot is easy to use. Only for Linux.

OpenShot Video Editor is a free, open-source video editor for Linux licensed under the GPL version 3.0. It can take your videos, photos, and music files and easily add sub-titles, transitions, and effects, and then export your film to DVD, YouTube, Vimeo, Xbox 360, and many other common formats.


user1344: For Linux people:
Kino
It is a non-linear DV editor.  It has many features including capture, editing, FX, and export to other formats.
I've used it for several years without issue.

user4645: If you're on Linux, consider Cinelerra: the most powerful video editor for Linux, Openshot: simple, powerful, and free video editor for Linux, or Kdenlive (also available for FreeBSD and Mac OSX): Free and open source video editor for GUN/Linux and FreeBSD
Openshot and Kdenlive can be installed via apt-get install, however Cinelerra requires a little more configuration

user11997: If you are really adventurous why not give Blender a go? It is a 3D animation and compositing/tracking application. It is completely free and open (FLOSS) as well as being totally system agnostic. Run on Windows 32bit or 64 bit, MacOS 32 or 64 bit and Linux 32 or 64bit.
The video editor is rather novel and a bit rudimentary but is supported by a large compliment of addons or python scripts that enhance its usability.

user159: I personally run Cinelerra CV and it's "mochup" Cinecutie on my Linux boxes.
Cinelerra (and it's relatives) can do some very sophisticated editing work, but they aren't the easiest to use.  Luckily, there are lots of video tutorials out there to help you.

user1506: There is an Linux/Gnome based video editor called PiTiVi which is working close with the GStreamer multimedia framework which is used by most Linux distributions. The PiTiVi project has been slow moving because of their development philosophy which is "upstream first". Challenges they encounter in GStreamer means that they work with GStreamer to solve the issue instead of working around the framework.  

user2206: Kdenlive is rapidly becoming the most advanced FLOSS video editor. Kdenlive supports Linux and Windows natively. There is also a version for macOS on macports.org, but it is outdated.
I use Kdenlive often on my Linux system. It has an active development team that are very responsive to new feature requests and bug reports. The user community is also very friendly and supportive.

user1232: You might want to see Wikipedia's Comparison of video editing software and list of video editing software. From my personal experience I recommend Kdenlive over any others. It has good support for a wide range of non-linear video editing functions. If you are the real geek, you may want to try out Cinelerra.

user763: VLMC is a non-linear multitrack editor. It's based on VLC and inherits a pretty vast format compatibility from that. The UI is a little rough, but it gets the job done.
Lightworks is a more recent project and seems polished. It's rooted in broadcast editing, so a large number of familiar codecs are unsupported. It supports Matrox codecs, which you have to install separately, so you'll have to convert your video to Matrox AVIs first.
Avidemux is a simple editor, good for trimming and small tasks. In my experience, not very stable on Windows, OK on Linux.

1364: <p>Sure, I could Google and find random software. But I rather have the opinion of users that have had hands-on with any open source video editors.</p>

<p>So if you've used one that you like or know of any, please let me know and state whether you've used it or just know of it (and heard good things). Thanks.</p>

<p>I'm looking for Windows software. But you may suggest Linux as well for other people that might stumble upon this.</p>
 18314: <p>Better than mearly good is AviSynth: <a href="http://avisynth.nl/index.php/Main_Page" rel="nofollow noreferrer">http://avisynth.nl/index.php/Main_Page</a> .</p>

<p>Basically you write a Script and then open the Script in a Player. The Script can change the input in many ways and there are many 1000's of Plugins. There are a few Forks including some 'traditional' looking Editors that use AviSynth under the hood.</p>

<p>After tweaking the Script precisely you simply 'copy' the Script (possibly with Ffmpeg) and render a final version.</p>

<p>Includes capabilities to express exactly (to the pixel and frame) what you want. Not too bad a learning curve and so many examples available. During several years of use I discovered no Bugs but apparently others found a couple that have since been fixed. Open Source and you assistance is welcome.</p>

<p>Often used in conjunction with VirtualDub to provide a GUI.</p>
 95: <p>A friend of mine liked <a href="http://www.virtualdub.org" rel="nofollow">VirtualDub</a> quite a bit, which is free. I have not, however, used it myself.</p>
 2459: <p><a href="http://www.openshot.org/" rel="nofollow">OpenShot</a> is easy to use. Only for Linux.</p>

<blockquote>
  <p>OpenShot Video Editor is a free, open-source video editor for Linux licensed under the GPL version 3.0. It can take your videos, photos, and music files and easily add sub-titles, transitions, and effects, and then export your film to DVD, YouTube, Vimeo, Xbox 360, and many other common formats.</p>
</blockquote>
 1344: <p>For Linux people:</p>

<p><a href="http://www.kinodv.org/">Kino</a></p>

<p>It is a non-linear DV editor.  It has many features including capture, editing, FX, and export to other formats.</p>

<p>I've used it for several years without issue.</p>
 4645: <p>If you're on Linux, consider <a href="http://cinelerra.org/">Cinelerra</a>: the most powerful video editor for Linux, Openshot: simple, powerful, and free video editor for Linux, or Kdenlive (also available for FreeBSD and Mac OSX): Free and open source video editor for GUN/Linux and FreeBSD</p>

<p>Openshot and Kdenlive can be installed via <code>apt-get install</code>, however Cinelerra requires a little more configuration</p>
 11997: <p>If you are really adventurous why not give <a href="https://builder.blender.org/download/" rel="noreferrer">Blender</a> a go? It is a 3D animation and compositing/tracking application. It is completely free and open (FLOSS) as well as being totally system agnostic. Run on Windows 32bit or 64 bit, MacOS 32 or 64 bit and Linux 32 or 64bit.</p>

<p>The video editor is rather novel and a bit rudimentary but is supported by a large compliment of <a href="http://wiki.blender.org/index.php/Extensions:2.6/Py/Scripts/Sequencer" rel="noreferrer">addons or python scripts</a> that enhance its usability.</p>
 159: <p>I personally run <a href="http://cinelerra.org/">Cinelerra CV</a> and it's "mochup" <a href="http://sourceforge.net/projects/cinecutie/">Cinecutie</a> on my Linux boxes.</p>

<p>Cinelerra (and it's relatives) can do some very sophisticated editing work, but they aren't the easiest to use.  Luckily, there are lots of video tutorials out there to help you.</p>
 1506: <p>There is an Linux/Gnome based video editor called <a href="http://pitivi.org/">PiTiVi</a> which is working close with the GStreamer multimedia framework which is used by most Linux distributions. The PiTiVi project has been slow moving because of their development philosophy which is "upstream first". Challenges they encounter in GStreamer means that they work with GStreamer to solve the issue instead of working around the framework.  </p>
 2206: <p><a href="http://kdenlive.org/" rel="nofollow noreferrer">Kdenlive</a> is rapidly becoming the most advanced FLOSS video editor. Kdenlive <a href="https://kdenlive.org/en/download/" rel="nofollow noreferrer">supports Linux and Windows natively</a>. There is also <a href="https://ports.macports.org/port/kdenlive/" rel="nofollow noreferrer">a version for macOS on macports.org</a>, but it is outdated.</p>
<p>I use Kdenlive often on my Linux system. It has an active development team that are very responsive to new feature requests and bug reports. The user community is also very friendly and supportive.</p>
 1232: <p>You might want to see Wikipedia's <a href="http://en.wikipedia.org/wiki/Comparison_of_video_editing_software" rel="noreferrer">Comparison of video editing software</a> and <a href="http://en.wikipedia.org/wiki/List_of_video_editing_software" rel="noreferrer">list of video editing software</a>. From my personal experience I recommend Kdenlive over any others. It has good support for a wide range of non-linear video editing functions. If you are the real geek, you may want to try out Cinelerra.</p>
 763: <p><a href="http://trac.videolan.org/vlmc/">VLMC</a> is a non-linear multitrack editor. It's based on VLC and inherits a pretty vast format compatibility from that. The UI is a little rough, but it gets the job done.</p>

<p><a href="http://lightworksbeta.com/">Lightworks</a> is a more recent project and seems polished. It's rooted in broadcast editing, so a large number of familiar codecs are unsupported. It supports Matrox codecs, which you have to install separately, so you'll have to convert your video to Matrox AVIs first.</p>

<p><a href="http://avidemux.sourceforge.net/">Avidemux</a> is a simple editor, good for trimming and small tasks. In my experience, not very stable on Windows, OK on Linux.</p>
