Goto http://realsocialdynamics.blogspot.com/ Try clicking on any of the YouTube videos embedded in the posts. Nothing happens. In FireFox, you can click on the play button to start the video or click on the video to open its YouTube page in a new window. I recall this working in Safari 2.0, but I'm not 100% sure, so I'm not marking it as a regression yet.
Not a regression as the same behavior is seen with Safari 2.0.4 (419.3) with original WebKit on Mac OS X 10.4.10 (8R218). Here's how to set up Safari 2 for testing on Tiger after installing the Safari 3 Public Beta: http://trac.webkit.org/projects/webkit/wiki/UsingSafari2WithSafari3PublicBetaInstalled
Changed title since the problem does not apply to all YouTube videos.
I cannot reproduce this problem with Safari 4.0.4 on Mac OS X 10.6.2.