Do you know the video bitrate of the H.265 videos that are pixelating? I will say that Roku devices can't handle super-high bitrate files. Even streaming from my DLNA server Roku has a bitrate limit of around 160 Mbps. It can handle higher peaks, but steady bitrates top out fairly low. But I've played the same files from a USB stick and had the same bitrate limitation, so it wasn't a network issue.
I leave a USB stick connected to my Ultra 4850 full time, and I just checked it and I would call it "a bit warm". Not hot by any definition, but certainly warmer than just sitting in a drawer.
Total effective bitrate of the media file is less than 10 Mbps.
As far as how warm the device is, probably depends on how insulated the components are. Of of my drives, a very thin all metal PNY drive gets quite hot. A larger plastic Sandisk not as noticeable.
Are you seeing the same behavior I am seeing on step 1?
If you’re asking if I see the message asking for access permission, I did see it the first time I inserted the drive but I’m not aware of seeing it again.
