Having quick access to handy tools is a must for any profession, no less so for VO artists. Voice talent J. Christopher Dunn has compiled a list of Five Must-Have Online Gizmos for Your Voice-over Toolbox that you'll want to check out.
I'm no lawyer (and I won't even play one here), but I would like to add a caveat regarding item # 4, "Save the Video". It's true that services like the one mentioned can grab online video, giving you the flexibility to post it to your site/blog/YouTube etc. However, just because you can grab it doesn't mean you should. Moreover, one shouldn't assume that a client's lack of response equals a "yes" when requesting a copy of the finished item. There is some debate about this; YouTube's own user agreement essentially states that once a video is uploaded, that clip is fair game for anyone's use. However, many of the content providers have legal decrees stating quite clearly the opposite. Unless you want to be potentially caught in a legal crossfire, your best move is to stick with content for which your client has given you the go-ahead.
Okay, enough finger-wagging. Go check out the toolbox and enjoy.