So, I found this extremely interesting thing today. Editing in the middle of 1 frame has always been a thing that people have wanted to increase precision within the game. I believe I found out a way to do this.

When you go slo-mo while watching a replay, you can use shift + p to go through what normally is frame by frame. In slow motion as in 0.20 this lets you pass through a single frame on several uses of the shortcut. Now you can press E to edit the replay while having it paused in the middle of the frame.
I only found this out 10 min ago, so I'd like you to discuss if this is actually a thing or not, I might be missing something. Oh, and this also seems to work fine on saved replays without glitching them.