I have a video URL like http://www.youtube.com/watch?v=AAAAAAAAAA
How can I get a RTSP URL for this video?
Go to this link, and Replace "VIDEOID" with the actual ID of the video you want:
http://m.youtube.com/add_favorite?v=VIDEOID
then right click the image of the video, and copy the link.
For example, if the video is http://youtube.com/watch?v=ABCDEFGHIJK, you would request http://m.youtube.com/add_favorite?v=ABCDEFGHIJK
The link is affectively permanent, but it will vary depending upon whether or not you are logged in and what preferences you have set when you request the page.