This indicates "High Definition" (HD) quality. Specifically, it means the video has a vertical resolution of 720 pixels, typically with an aspect ratio of 16:9 (

It is highly likely that is a private file name —potentially a system-generated name from a screen recording, a downloaded social media clip, or a file stored in a personal cloud drive.

The alphanumeric string "7JTJmZjI" is likely a unique hash or identifier used by a server to prevent file name duplication or to track the file within a database.