Probably not doable but I will suggest anyway. It would be over the top nice to have a second image which is right before the current image, for easier cutting, if you really don't want to miss anything. This second image should not have any priority because it will be much later visible then a key frame.
I don't know if this is feasible, but maybe with nvme storage and many cores and RAM it can be done nowadays? But it never should slowdown the main image in the first place.
Thanks for this great program anyhow.
Yes it would help to have the option to display the previous image in cutting mode (maybe as a smaller 1/4 x 1/4-size overlay, displayed when paused).
I don't believe a filter could do this, currently at least.
I haven't used avisynth with avidemux, but maybe an .avs script could be used to try out the idea ?
You save the resulting project with your cutpoints, then change the source to your actual video. Avisynth doesn't have keyframes, but I think it's possible to display the keyframe status on screen.