: These are likely "release tags" or the names of the groups/sites that encoded and uploaded the file.

: Also known as H.265 , this is a compression standard that allows for high video quality while keeping the file size significantly smaller than older formats like H.264. HD : Confirms the video is in High Definition.

: HEVC files require specific codecs or versatile players like VLC Media Player or MPC-HC to run smoothly. To provide a more detailed write-up,