Basically, I've been seeing alot of people using the good old "use youtube, post, then edit flash values" thing, when there is a MUCH simpler way.
First, start by doing your standard FLASH tags, I.E;
[flash(x,y)][/flash]
The X and Y are replaced with your normal width/height options. Fairly easy so far. Now here's where.. it doesn't get any any more difficult whatsoever.
And then, when you copy a youtube link, the link usually looks like this.
Notice the /v/, followed by the video ID. It's that simple.
This is because of youtube's several new skins. They've changed their PHP scripts around quite alot, and if you copy the link above and paste it in your browser, you'll notice it's simply the youtube flash player, and not everything around. The /watch function draws the entire page of youtube, and the /v/ contains the flash player.
Maybe not so simple as I find it, but moving on.
Now, instead of using ye olde 'use youtube and post then edit', simply do this;