The [embed] tag has been disabled for security reasons (thanks bacon for pointing it out). Not a problem, but could have been. If you think you have a legitimate need to embed stuff please let me know. The [youtube] tag is still fine (mainly because it's constrained to Youtube and Youtube alone). The [embed] tag was open to cross site scripting attacks (indeed Vimeo was redirecting people to a different site).

If you desperately need to embed something it would be better to create tags specifically for those media, rather than accepting any url. So please let us know.

Also the [flash] tag works in a lot of cases, with some creative thinking.

How does it really work?