(e.g., Telegram download, email attachment?) What device are you trying to play it on?
If you need to change the file format for compatibility (e.g., to MP4 for a TV) or change its name: AgADgwADyby5Vw.mkv
Matroska Video, a flexible, open-standard video container format that can hold a high number of video, audio, picture, or subtitle tracks in one file [1]. AgADgwADyby5Vw.mkv
Knowing this will help me tell you exactly which player or converter to use. AgADgwADyby5Vw.mkv