These refer to High-Efficiency Video Coding. It’s a compression standard that allows for high-quality video at a much smaller file size than older formats.
This is likely the "tag" or watermark for the specific website or upload group that processed this version of the file. Important Note on Safety and Legality These refer to High-Efficiency Video Coding
The video resolution (HD), meaning it has 1,280 pixels across by 720 pixels down. meaning it has 1