Best way to compress 100gb video file?

I'm really not sure what happened. Usually for four hours of footage, the files are around 5GB and acceptable quality. I apparently didn't manage my disk space well enough though, and ran out in the middle of recording. When I went to look at the file to see how much of it was preserved, it was randomly a whopping 100GB!

Trying again after clearing some space and all the other videos are the normal 5-6GB file size. I'm not sure what happened, maybe some kind of glitch when I ran out of space or something, but even then it would have had to get to 100gb before I ran out in order to fit on my hard drive at all.

Regardless, I would like to preserve this video if at all possible. I don't upload these anywhere, but I save them for the memories (DND sessions). I tried using Davinci Resolve, but because the file is so large, it doesn't seem to work when I try to import it into my workspace. Anyone know a simple program I might be able to use to compress this? It doesn't need to be lossless or anything, long as it's at least mostly viewable