File types supported by Windows Media Player - Microsoft Support
It is almost certainly a video file using the MP4 (MPEG-4 Part 14) container . This format commonly stores video, audio, and metadata tags like title, artist, or creation date. 26770mp4
The number "26770" is very similar to part numbers for high-performance storage, such as the WD_BLACK SN770 series. If this text appeared in a system log, it might relate to a media file stored on or processed by such a device. File types supported by Windows Media Player -
Many digital video recorders (DVRs) name files with long numeric strings (timestamps or IDs) followed by ".mp4." and metadata tags like title