I recorded a first-play demo using Fitz 0.85. Playback locks up when the map reloads after difficulty selection. I don't remember if cross-map demo playback is supposed to work in 0.85 or not?
Playing back the demo using Mark V works across the map reload though, and at least for the next few minutes... I haven't watched the whole thing to see if anything breaks later. FWIW, here it is:
https://dl.dropboxusercontent.com/u/11690738/temp/jlaw_back_hard.zip
For me, in the fights with the crushers in the room I was always kind of running around with my hair on fire; couldn't use the crushers effectively. I think I tried once or twice but just managed to get myself into more trouble.