Replay Mod Forums

Ver. 1.11 - only 1 mod installed (ReplayMod v1.11)
Windows 10 Pro x64
Forge 1.11-13.19.0.2184
Java 1.8.0_111-b14

I can load this replay , it occurs only on this replay and at any time in it, i can move around, fast travel to anypoint in time of the replay, but every time i click on the button to add a keyframe (position or time one) it say "loading entity positions : [percentage here]%", if the replay is paused it stay at 0% and if it's playing it goes well 'till 100% when it stop and do nothing.
Also it prevent me from doing anything with the HUD, shortkeys still work but the HUD is totally freezed.

I recently re-installed windows and didn't yet have installed ffmpeg, could it be the problem ? i thought it was used only when rendering...

Anyway early thanks,
and i loved the mod in 1.8, would love to use it as fast as possible in 1.11 !