Here it is:
https://1014.org/_/subtraction.zip
224MB -- I re-encoded the video files down to a really low bitrate (1.5mbps vs the original 25mbps) to keep it manageable in size. It looks a bit crap but you get the idea.
That link will only be valid for a few weeks so if you want it, get it now!
The baseline tracks have a "sample and hold" preset on it that avoids having to decode the video file (making it perform better) -- if you removed this, it'd still work, but probably look a bit different as the noise profile of the background would change...
The way all of these FX interact is really fragile, I think after doing this I improved the way FX presets can get frames from other tracks/etc. but I forget.