Video in Flash 8 and Alpha? What?

I am puzzled: Can some explain what the heck Alpha and video has to do with Flash 8. I see some cool video tricks, like a guy walking on a flash site with a white back frop. How do you loose the back ground without shooting infront of a bluescreen?

Is that even possible. I normall use a white background and balance the tones with lighting or on campus use the blueroom. That is a lot of work - if I can get rid of the background in flash digitally please drop me some hints… I beg of u…

Dammmmm my coffee pot is empty… be right back guys…