exFat on Devant TV: filesystem FAT32
The obligatory holiday watch - "Home Alone". The USB stick wasn't showing up at all because it was still formatted as exFAT. I even format the USB 3 times. Maybe it's the filesystem..FAT32 or NTFS..I think. Devant apparently like most TVs only reliably reads FAT32.
Quick terminal fix:
sudo pacman -Syu dosfstools
sudo wipefs -a /dev/sdc
sudo parted /dev/sdc --script mklabel msdos
sudo parted /dev/sdc --script primary fat32 1MiB 100%
sudo mkfs.vfat -F 32 -n MOVIES /dev/sdc1
Plugged it back in, movie appeared instantly!