: This is a unique alphanumeric identifier. In many web ecosystems, specifically YouTube, this 8-to-11 character string acts as the "Video ID."
If you have encountered this file in an unexpected location, such as an email attachment or a random folder on your computer, exercise caution: KxrvR5vE_720p.mp4
If you are looking for a of the video's actual content? If you need help opening or converting the file? : This is a unique alphanumeric identifier
: Tools used to save offline copies of streaming media often append the resolution to the ID so users know the quality of the file. KxrvR5vE_720p.mp4