Because of the various requests for help downloading videos from YouTube to view off-line on the computer, I’ve looked through a variety of ways to do it, especially for free, and it seems that most of the download/decode websites have stopped working with YouTube, maybe since Google bought it. Hmm. So what’s to be done?
Start with using the FireFox web browser, if you aren’t already using it. (You’re NOT using Explorer still, are you??)
Next, download the DownloadHelper plugin for FireFox:
Install DownloadHelper and restart FireFox. Here’s a video to hep you use it:
The files are downloaded with the extension .flv — Flash Videos. You can view them with a FLV Player:
- http://www.martijndevisser.com/blog/flv-player/ (Windows only)
You can also use a converter, like the free MediaCoder, to turn the FLVs into a different format, like QuickTime or AVI.
- http://mediacoder.sourceforge.net/download.htm (Windows only)
If you have a Mac, you can add a free plug-in, Perian, to QuickTime Player, to allow it to play a variety of video codecs:
If you have the free QuickTime Player, you can just play the .flv files, but if you have paid for QuickTime Pro, you will be able to save the .flv files as .mov (QuickTime) files with this upgrade.
If you don’t have QuickTime Pro, and want to convert the FLV files to QuickTime for free on a Mac, try iSquint:
You will be constantly prompted to purchase their other video product, VisualHub, but just say no. 
Happy New Year!
