Get a Youtube account. Upload your video. You will be redirected to a page with code that you can cut and paste into a post when you upload the video.
With YouTube, there will be a button that says "Embed".
When you press that, a bunch of code gets puked out in a drop down window.
Copy the whole thing... then paste it directly into a post.
YouTube code is littered with unnecessary stuff. Prune it so the post looks nicer. Delete everything before <Embed
And delete everything after the last </embed> like this:
Wat should be left is a little code that looks something like this:
*Hint*
Press the "Preview" button at the bottom of the post before pressing "Submit". Here is the preview of my example video:
Now don't go looking for any significance with the video that is used for the example... it was on the front page of YouTube!
Hope it helps!
Craig