user4196: Here is my situation. I'm doing a series of lectures for a Udemy course and I need to show people how to boot into tails from a USB drive. Obviously while configuring the bios and when in the new O.S it is impossible to run a software screencast solution thus I need some form of hardware to frame grab. 
I've never done this before and I need some help to understand the basic concepts and what I should buy. I understand this question isn't quite in a stackexchange format thus at the very least if you could point me to a forum that could answer this question or a tutorial you think would be helpful, then I'd be very grateful

user-1: You can use a graphics card that has a HDMI output connector.
Instead of connecting it to a monitor/TV you can connect it to a camera or a VCR that has HDMI input. This way you should be able to record anything that is shown at the card.

4196: <p>Here is my situation. I'm doing a series of lectures for a Udemy course and I need to show people how to boot into tails from a USB drive. Obviously while configuring the bios and when in the new O.S it is impossible to run a software screencast solution thus I need some form of hardware to frame grab. </p>

<p>I've never done this before and I need some help to understand the basic concepts and what I should buy. I understand this question isn't quite in a stackexchange format thus at the very least if you could point me to a forum that could answer this question or a tutorial you think would be helpful, then I'd be very grateful</p>
 -1: <p>You can use a graphics card that has a HDMI output connector.</p>

<p>Instead of connecting it to a monitor/TV you can connect it to a camera or a VCR that has HDMI input. This way you should be able to record anything that is shown at the card.</p>
