Pastafreak, now there isn't a special box for it you just paste the full YouTube URL into your answer. It's worked for me on the few occasions I've used the feature until I tried copying the Jussi Bjorling link on a different thread. Three attempts - three failures. As you see, other posters have been similarly frustrated.
I find that if I post or open You Tube links when I am on Chrome I get sound but no vision. If I switch to Firefox I get both. Puzzling, this predates the update though.
Mine didn't...and I copied the link via "share" on YouTube.
I tried doing one earlier...and noticed that the saved link had a full stop within "youtube".