There's a [youtube] tag now.

EDIT: I assume tags have to be typed manually for now (unless I'm dumb and missed something to click for it)?
Yeah, you have to type them until I get a nicer editor in.

I assume tags have to be typed manually for now (unless I'm dumb and missed something to click for it)?

I made a full-featured editor for you. http://jsfiddle.net/3946w/

EDIT: Ah, okay. So there's where the limitations are.
If you have found a way to fail to make a youtube video that should have been valid, don't hesitate to share it. Was there a link that broke the tag?

I didn't read above.

/watch?v=xxxxx is okay.

/watch?v=xxxxx&others is not.

/watch?v=xxxxx&others should be okay

/watch?others&v=xxxxx will not match although it is possible to create links like this while fiddling with youtube playlists

Created a patch to deal with this and filed a pull request.

I assume tags have to be typed manually for now (unless I'm dumb and missed something to click for it)?

I made a full-featured editor for you. http://jsfiddle.net/3946w/

I should probably toss something like this on the editor.

/watch?v=xxxxx&others should be okay
/watch?others&v=xxxxx will not match although it is possible to create links like this while fiddling with youtube playlists

Created a patch to deal with this and filed a pull request.
merged the request and updated the site.

EDIT: I assume tags have to be typed manually for now (unless I'm dumb and missed something to click for it)?

no longer!