Any "Alpha Over/Under" video tutorial outhere??

Hello, this is a noob question
Is there any video tutorial about using “Alpha over/ under” from the sequence editor?
I am learning how to make a video background see through at the moment.
The reason why I am specifically asking for a video tutorial is because I just saw the Glow effect video last night, and I found it terribly easier and more helpful than usual. Anyway, if you happen to know any tutorial concerning the subject , would you please post it (doesn’t have to be a video)
thanks alot!

PapaSmurf has several VSE and composting Tuts on Vimeo. You might want to start with this one:

ICAWB page 384-5 … if you’re on dail up!!