Some users with laggy playback

[TheDreadPirate]

AFAICT, your server is performing fine in terms of transcoding. And if it can transcode then it can direct play. The bit rates on these videos aren't stupid high. The clients are plenty capable and it isn't isolated to one client. The only thing that makes sense is some network issue. But it sounds like if it is a network issue it is transient so that makes it hard to diagnose.