To embed or see a video within a post, TRY the following.

First upload your video to www.youtube.com

than on the right side of the youtube video page you will find a box marked "url". Copy the text in the field.

For example it will look like this.
http://www.youtube.com/watch?v=2pNKBuz1MaQ

Then copy everything after the "watch?v=".
So in the above example we will use 2pNKBuz1MaQ

Then type the following but use yt instead of xx
[xx]insert what you copied above[/xx]

So in the above example we will have this
[xx]2pNKBuz1MaQ[/xx]

And if all goes right you will see the video below.