How to use/combine a "matte" .mov with a video in photoshop?

I am working with video in Photoshop for the first time.
Unfortunetely I can't work with AfterEffects so I try to make my first clip in Photoshop CS3 Extended.
I downloaded an amazing "explosion" .mov file.
In the downloaded zip file there was a second black-and-white .mov version of the explosion (imagine a "white explosion" in black background like an alpha channel) called "matte".
How may I combine these two videos so that the background of the original video can be transparent?
In other words how can the "matte" called .mov work as an alpha mask for the original video?
Does the Photoshop has this capability?

Thankyou very much!