😭 I corrected it now

If you want to compress video files, you’ll need to reencode them. Maybe using something like HEVC (High Efficiency Video Codec). But for 80GB of videos, you’ll be there for a while and probably won’t shrink them enough to be worth it. It would likely take less time to simply re-download the files later, even with a mediocre internet connection. In practical terms, you won’t get that 80GB to be any smaller.

ISOs don’t compress anything, as far as I know, or at least not by default. I think they’re basically just a container.

To reencode your videos, you can use the free HandBrake.