Since the filename itself doesn't describe the video, you can try the following to figure out what it is:
: Files with these alphanumeric names are usually cached media or direct downloads from a private chat, group, or channel. How to identify the content AgADHwgAArdTsFY.mkv
: Revisit the chat or website where you obtained the file; the surrounding text or "caption" usually provides the context. Since the filename itself doesn't describe the video,
: The .mkv extension indicates it is a Matroska Video file, a high-quality container that can hold video, multiple audio tracks, and subtitles. multiple audio tracks
: Use a tool like MediaInfo to see the technical details (encoding date, software used) which might hint at its origin.