Some Android file managers rename media this way when moving files between folders or SD cards.
The name serves as a timestamp, allowing for easy chronological organization: The video was recorded on September 27, 2021. 2021-09-27_15-53-52 video0mp4
The recording started at 3:53:52 PM (using a 24-hour clock). Some Android file managers rename media this way
This usually indicates it was the first file in a sequence or captured by the primary camera lens. 2021-09-27_15-53-52 video0mp4