I wouldn’t really recommend this for a full movie, but after seeing very lacking results from AI video upscalers, both in quality and ridiculous file sizes, I found interesting and surprisingly good results in extracting individual frames from videos, using an AI upscaler on the frames, then stitching them back together.

I’ve been doing this for some old/low res personal videos and some of the upscaled videos have even come out smaller than the originals despite being better quality.