SOLVED: Jellyfin buffering... is my hardware acceleration working?

[TheDreadPirate]

You would see an ffmpeg process if it was transcoding.  But you probably aren't transcoding, based on what I saw in your last post, so you wouldn't see ffmpeg in intel_gpu_top.

Did all of this except for the "delete segments" part; I don't see that setting.

I just noticed you are on 10.8.9, which is why you don't see "delete segments".  That was added in 10.9.

I highly recommend you upgrade to 10.9.10.  At a minimum, 10.8.13.  There were several security vulnerabilities that were patched leading up to 10.8.13.  And the problem you are having may have been a bug that's been resolved in a later release.  Your specs and your Internet connection seem to be up to the task for the media you are serving.

Regardless if you stick with 10.8.13 or upgrade to 10.9.10, backup your jellyfin data.

/var/lib/jellyfin
/etc/jellyfin

Both of those directories contain your permanent Jellyfin data and your configs, respectively.