The source website where the file was hosted.
Matroska Video, a flexible container format that can hold multiple video, audio, and subtitle tracks in one file. Phoenix 2020 (TV Series 2020–2021) - IMDb
HEVC (High Efficiency Video Coding), also known as x265, which provides high quality at smaller file sizes.
"UnRated" (typically indicates extended or uncensored content). Source: HDRip (High Definition Rip).
