It's very easy. When clicking "submit" you will see a big blue button that says "my" in it. If you click on the button, the following appears in your content:

Bmyspacetv videoID|430|346}

Where it says "videoID" simply place the numbers from the myspace video url. So here is a url for a myspace video:
http://www.myspace.com/index.cfm?fuseaction=vids.individual&VideoID=25687206

Copy and paste "25687206" to replace the words "videoID".

Wherever you place this in content it will work. Try it here if you want to, it's simple.

Note: Where it says Bmyspacetv videoID|430|346}, replace the "B" with "{"

I had to replace it with something else so the video did not pop up.