Video with alpha

Hello! I need to load video with alpha into plane.
I tryed to do different things:
Load 2 videos, one with alpha, one with rgb. Good solution, but sometimes videos become unsynchronized=[
Load 1 video, where on upper side is rgb, on down side is alpha, and tiling it and use uvoffset to combine it to texture with alpha. This works perfect, but alpha doesn’t work on ios devices.
I load ~900 frames and animate it frame by frame, but i can’t reach a 30 frames per second on mobile phones with that.
Chromakey shader don’t good solution, because it cannot have normal edges.

Do you know what else can I do?