--device /dev/dri --mount type=tmpfs,destination=/tmp,tmpfs-size=16000000000 --no-healthcheck
Use this in Plex's Transcoder section in the webapp...
/tmp
If you had 64GB's of RAM and wanted to use a 24GB RAM drive for transcoding, the line will be...
--mount type=tmpfs,destination=/tmp,tmpfs-size=24000000000
Thank Ibracorp on YouTube for my knowledge on this subject!