Posting YouTube videos is messing up threads?

Is there any explanation why when I post YouTube videos in a thread, the format of the thread goes completely wonky? I never had this problem prior to last week.

I normally just paste the link and bam, it appears, no issues. Now no matter what I try, it displays the video but the thread format is completely skewed. Edit/Quote/etc buttons get pushed all about the screen. Just... weirdness.

Https always does that, it seems. Drop the "s" at the start of the URL and everything goes fine.

EDIT:

http://www.youtube.com/watch?v=WeWpCJruFlw

See?

Interesting. Wonder why the https messes things up. Thanks for the help.