Does alpha matte version of a clip allows to change the pattern
Changing the pattern of the paper will be too difficult, because you would have to map the pattern around the roll, too. But you can change the color with some Hue/Saturation/Value effect. 

So, what are the black/white alpha-matte sections for? The author had to append them at the end, because in the process chain at Shutterstock the video could be transcoded and the alpha channel could get lost. In your own video editor you will have to cut these black/white sections out and re-apply them as alpha clip over your color clip. How to do this can be different in After Effects, Final Cut Pro, ...

But now the most interesting part. Why did the author append two alpha-matte versions, which seem to be equal?

Only after calculating the difference between the two versions I saw it. In this picture gray means that the pixels of the two images are equal, and black or white means that there is some difference.



This means that the first alpha-matte is for the paper including the white ripped edge, where-as the second one is for the paper surface without the ripped edge. If you want to color the paper, apply the effect just together with the second alpha-matte, and the edge will stay white.