Vdx_10_ev.mp4

The filename appears to be a specific video file, possibly a demo or "evaluation" clip (denoted by "ev") used for technical testing. While "deep piece" is not a standard industry term, it likely refers to one of two things in this context:

Knowing if it was in a professional video editor or a personal download folder could help pin down its exact purpose. vdx_10_ev.mp4

In creative circles, a "deep piece" is often used to describe a work of art, music, or video that is intensely personal, reflective, or addresses serious themes like vulnerability and personal growth. The filename appears to be a specific video

If this file appeared on your device unexpectedly, it may have been saved through a management app like the VDX Video Downloader. If this file appeared on your device unexpectedly,

Given that "vdx" often associates with video codecs like DivX 10 and technical forums discuss Dolby Vision/HDR profiles for similar file types, this could be a "deep color" test file. These "pieces" are used to evaluate how well a screen or player handles high-bitrate video or "deep" color depths.