: You exported your library, and Google renamed files to prevent naming conflicts during the bulk download.
: You saved a video from a shared link or album where the original filename wasn't preserved. B63kXx7MNixC1CPxJ4SeIsvkruFHZrRU.MP4
: The .MP4 format is a digital multimedia container most commonly used to store video and audio. It is highly compressed, making it the standard for web streaming and mobile devices. : You exported your library, and Google renamed
Since the filename is randomized, you can find out what the video is by: : You exported your library
: You downloaded the video directly from the Google Photos web interface. How to identify the content