Crossfade between two Video using via a (third) alpha mask

EDIT: SOLVED (MY STUDENT GOT HELP FROM THE FORUM IN ADVANCE)

Hey there,

I hope you are doing well?

I haven't used jitter for couple of years and I'm a quite a bit rusty, unfortunately.

For an art installation a student of mine wants to create a slow crossfade between two 4k videos.

The complication here is that he wants to use a matrix of complete black or white pixels to interpolate between the two videos. (every white pixel in the matrix should be video A and every black pixel should be video B).

I suppose jit.pix. might solve that problem, but I honestly forgot how this might work.