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 (
The identifier does not correspond to a publicly recognized or widely known video, viral hit, or specific academic subject. On platforms like YouTube, video IDs are typically 11 characters long (e.g., ://youtube.com ), and 7JTJmZjI is only 8 characters. 7JTJmZjI_720p.mp4
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. This indicates "High Definition" (HD) quality