> How would a downloaded file buffer
I've no idea. It happens sometimes and only seems to happen with certain fils. In this case I'm sure it's a jellyfin issue, but this just comes down to having to debug while someone is waiting to watch - which is exactly the time I don't want to.
As for language/subtitles it's true if it happens from the start (which I agree, is usually true) but occasionally the downloads get weird midway through.
At that point you’re not playing the downloaded file. You’re either playing a transcoded version of it which will buffer as a computer tries to convert on the fly. Or you’re dealing with a network throughput issue related to the bitrate of the file you’re trying to remotely play.