YouTube videos may now be embedded in comments again. The procedure is the same:

1) Browse to a YouTube video.

2) Copy/paste the web address of the video (shown at the top of your browser window - not the YouTube embed link!) into the comment.

3) The address will be automagically converted into an embedded video in your comment.

Since some browsers tend to choke on pages that contain a large number of embedded videos (cough Internet Explorer cough), there is a limit of 25 videos on each page of comments. After 25 videos are posted, the YouTube URLs will simply be converted to links that go to YouTube, instead of embedded videos.

UPDATE at 12/26/08 5:03:46 pm:

Just forget that part about the limit; a new technique lets us completely remove the limits on embedded videos. An embedded video now appears in a comment as a video-sized empty frame with a link at the top that says “YouTube Video.” Click that link, some Javascript magic happens, and the video appears in the frame, ready to play.

No limits.

UPDATE at 12/26/08 5:49:29 pm:

Please note that since there’s no real information about the contents of the video in the initial empty frame, it’s a good idea to include a short description in your comment, to let readers know what they can expect if they click the video link.