Thanks for the code. It really helps in my work on my site.
Banisher, It depends on where you want to use it.
If you want to put some videos on a post at your forum the code is the one Chamf said.
But if you want to put a video in your main page home or etc.
you will need an html script code. on youtube says embed.
so the code for the video you want appears on a page except you forum is something like this:
<object width="425" height="344"><param name="movie" value="http://www.youtube.com/v/y8Kyi0WNg40&hl=en"></param><embed src="http://www.youtube.com/v/y8Kyi0WNg40&hl=en" type="application/x-shockwave-flash" width="425" height="344"></embed></object>
Hope to help you.