How to change patterns in a clip with an alpha matte version

Question

I'm a beginner in this field and I have to buy this clip from shutter-stock.

This clip comes with some pre-rendered patterns and has an alpha-matte version.

My question: I want to use different pattern for the ripped paper, how can I achieve that? Can the alpha-matte version used for this purpose? if no, what is it used for?

Answer 1

If you have only rendered clip, you can use only this 5 textures.

To change texture you need a source file (i don't know how author realised it, maybe it After Effects or 3Dsmax or both or another program).

First alpha for paste object inside white area with imitation of volume (pasted object behind prerendered). Second - for paste object without imitation of volume (over those ragged borders)

Youtube: Similar effect in Photoshop & After Effects

Answer 2

The alpha matte is supplied with that clip so you can use it as a mask to place objects/textures under the ripped paper animation clip. That shutter-stock clip is all pre-rendered footage, so unfortunately you can not change the texture in the animation.