9265599.mp4.mp4

Simply rename the file to remove the extra extension. It will still function as a standard MP4 multimedia container . 2. Random or System-Generated Identifier

Content Delivery Networks (CDNs) or databases often use numerical strings to identify assets. 9265599.mp4.mp4

The double extension .mp4.mp4 often occurs by mistake when a user manually renames a file. If a system is set to "Hide extensions for known file types," a user might see 9265599.mp4 and add another .mp4 to it, resulting in the actual filename 9265599.mp4.mp4 . Simply rename the file to remove the extra extension