First of all a rescan interval of 1sec does not seem sane to me 😉
Secondly, those look like mp4 video files, which Im not sure firefly even serves.
If you’re on windows on a decent PC, you can safely set the rescan interval to, say, 600 seconds (10 minutes). You might as well just enable “always_scan” in the ini file rather than force it to do a rescan every other second.
I guess the filescanner hickups when it iterates that fast.