Link to ModThis mod adds a bbc tag (with a nice button in post window too) to embed Stage6 videos in your posts, it's safe and doesn't need you to enable flash bbc on your board.
It's a modification of Yakuza's YouTube BBC code mod.
Syntax: [stage6=width,height]videoID[/stage6]
Example: [stage6=500,400]54322332[/stage6]