In my case, it's the Samsung Tizen client playing back from my WIndows Plex server, which grabs data from an unRaid storage server over LAN. I've bumped the transcoder throttle buffer down to 15 seconds. The spindown delay is set to 1 hour for my drives... but things are playing well past the 1 hour mark and the drives would not be spinning down while being accessed, anyway. The Windows server never sleeps. Not sure what else to check.