The filename likely refers to a private archive or a niche internal backup. Here are the most probable interpretations of the components:
There is no public record of a widely recognized media series, academic paper, or software project titled that corresponds to a video file named "prbackup ep 252.mkv" . prbackup ep 252.mkv
: This is a Matroska Video container capable of holding multiple audio and subtitle tracks. The filename likely refers to a private archive