Just a comment--Given how rigid both YouTube and Yahoo Video are about the content of video, I'm surprised you were able to find anything you wanted to download. 
You'd be surprised how much good stuff falls in the cracks

Update 1: ever since the Site Which Cannot Be Mentioned Here bought up imeem, life has sucked a bit for those of us who like to have MP3 versions of streaming music. However, with judicious use of Lala and the aforementioned
Video DownloadHelper Firefox extension, you can still have quite a bit of joy.
Update 2: I never did get around to installing
Hulu Video Downloader v3.18 (no idea why) but I did just see another program which purports to do the same thing:
StreamTransport v. 1.02 -- I hope I remember to install and try it

Update 3: Simple way to download YouTube video is to use Kiss YouTube. Just replace the "www." in front of the URL of the YouTube video you want to snag with "kiss", wait for the new page to load, and click the download button (the downward pointing arrow) or the HQ button (to download the video in high quality MP4 format). "Keep It Simple, Stupid" indeed
