Not sure if just on Firefox or broken in general.
Just posted something on one episode & tried both youtube types of tags (from the top bar of tagging text) to a pair of Hammer Studios movie trailers but the link wasn't working once the post was live. Went with the basic URL tag which worked.
youtube tag broken on firefox
"That's funny, usually the blood gets off on the second floor." -Mr. Burns in The Shinning episode (Treehouse of horror V)