Its really not that hard. Once you've got a basic media-player set up, you can just add a listener to watch for a mouse-over event and when the mouse is over, you increase the alpha until its not 100. If the mouse is not over and the alpha is not equal to 0, you lower it.

BTW, if you are requesting this job to be done, it should be in programming. I believe this is more of a help forum.