You can use [b][[/b]sjmBcm84iA4[b]][/b] as forum message to display youtube video, where 'sjmBcm84iA4' is youtube movie id
( http://www.youtube.com/embed/sjmBcm84iA4 is the same as http://www.youtube.com/watch?v=sjmBcm84iA4 )


http://www.youtube.com/watch?v=sjmBcm84iA4