Sorta as the guy above said.

You record the replay twice, one with each shader. Then just crossfade them. The longer the crossfade the smoother it looks.

To avoid "whiteout" between them (the middle of a direct crossfade will be a solid colour) place the second video on a seperate track, and fade the first one.

TBH the only difficult part is syncing the two clips because even being 1 frame off will cause ghosting.