Does it have to be HLS or is that just what the code allows right now? I think it's easier for people to host a single mp4 than it is to host a set of HLS files. I could submit a PR to add mp4 files if it makes sense to do so.
Discussion
Please do, you could also just drop and mp4 it might already work
I pushed out 4 PRs for your consideration: https://github.com/v0l/zap.stream/pulls
I wonder if it would make sense to combine the recorded stream and regular video content on the site and add an upload button to the recorded stream section.