This is not the first time we have talked about this subject. Brandon wrote an excellent article on it. There are several tools, but none quite as easy as pwnyoutube.com. It does not require you to download any software or even copy a url. Simply add “pwn” before “youtube.com” in the url of the youtube video you are viewing and that takes you to a pwnyoutube site where you can right click and “save target as” for the .flv file and even the higher quality .mp4 file where available.
If you are looking for a good video illustration to use in an upcoming talk, try this blast from the past:
Consume Me (DC Talk)