Barack Obama has made history, and I'm not talking about that whole "First African-American President" thing either. I'm talking about something important: The ability to download YouTube videos! Although no official announcement has been made as of yet, if you go to Barack Obama's YouTube channel, you'll note a "Click to download" link that allows easy downloading of Obama vids.
Hopefully, Google is rolling out the feature for all videos, although, given the historic conflict between big movie and television companies and YouTube, it might not happen -- can you image how many people would download and share videos that violate copyrights before YouTube had a chance to pull them?
In any case, a search on the Internets will reveal a number of programs that will allow for downloads of YouTube and other flash-based videos.