how do you put videos in your posts?

Basically, you use BB code tags.

Whenever you go to a YouTube video, it has an address like this(by the way, this is a random video I'm using as an example):

http://www.youtube.com/watch?v=r7C6W0M5ME0

Type [YOUTUBE]r7C6W0M5ME0[/YOUTUB] to add the video to the post(I left off the last E so it wouldn't work).

As in a youtube video?

1st: Go Advanced
2nd: Enter the Youtube Tags
3rd: Copy all letters after "v=" on your youtube video you want to show.
4th: Paste between the Youtube tags
5th: Post

Example:
Vid: http://www.youtube.com/watch?v=CNm8ZCJ7Fx8
Cut: CNm8ZCJ7Fx8
Paste: [YOUTUBE]CNm8ZCJ7Fx8[/YOUTUB]. "E" is off so you can see.
Done: