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