(e.g., Was it sent in a specific Telegram group or found on a hard drive?)
If this file is from an unknown source, do not open it . MKV files can occasionally be used to hide scripts or malware if the media player has vulnerabilities. AgADCQgAAjVlyVY.mkv
To help me provide a useful report, could you clarify the context of this file? For example: AgADCQgAAjVlyVY.mkv