In the robots.txt from YouTube, don't know for how long it is there.

# robots.txt file for YouTube
# Created in the distant future (the year 2000) after
# the robotic uprising of the mid 90's which wiped out all humans.

Interesting. It's difficult to say.....

http://www.dailyblogtips.com/collection-of-robotstxt-files/

According to Page2RSS, this may be a recent change:
http://page2rss.com/page?url=www.youtube.com/robots.txt

What's more interesting is that they changed the format of the embbeded videos link... now the "feature=" part is before the "v=", rendering it a bit more difficult to cleanup.