Why is this reversed footage stuttering?

Is there any other thing it can be rendered to that will be a decent export from cache, Ann ?

Since you understand the shutter speed ( at 180 equiv.) if you shoot at 60fps, it will be 120th / sec.

That would give you less blur per frame.  But you need twice as much light, or open up a full stop ( from 1/60th / sec. ).

H264 was fundamentally designed to 'watch' ( not edit ). It is heavily compressed footage. It looks nice. But it's not the best for editing. Luckily computers got really fast and powerful and now you can actually edit the stuff way better than say 10 years ago.

To keep down the weight of camera and internal electronics and using light weight SD cards, drone cameras typically use H264 for compression. The quality of the footage is pretty amazingly good, in my opinion. But it is still ( the H264) not the ideal editing codec.  No big deal.

When applying effects in the editor ( including reversing footage ) it requires the editor to take the frames and render them from the last frame (first) to the first frame ( last ), and that takes what Ann referred to as horsepower. Luckily you have a powerful computer and can do it. Apparently something is not working too great and it's related to the combination of your computer, the editing program, your source footage, and the effect(s) applied ( and to some extent how you shot it (frame rate / shutter speed )).

You might be able to set your render to something like I-frame only something or other … render it after applying effect, and when you export check 'use rendered cache if available' … see if that works.

It's kinda a crap shoot, how to fix things.

Good luck !

P.S. don't fly too far away !

Drone footage is heavily compressed. Also 30p is not very suited to be slowed down 60p would have been a better framerate.

Slowed down and reverse needs optical flow and Rendering (green).

Best is to use proxies with this kind of footage.

I wouldn't mind seeing the same footage sample(s) you have on that youtube site now playing on your link, to one using forward and put on youtube so I could compare them...

I don't see stutter, but does look a bit blurry (especially on full screen). Without comparing I'd be tempted to say try 60 fps (probably have to go down to 1080p to shoot that high frame rate ), and turn off image stabilization maybe .. who knows. Got nothin to compare it with.

It's not HORRIBLE the way it is... but is a bit on the 'not sharp' end... like a not so great lens kinda thing...