Instead of just downloading, tap the three dots on the top right of the message and select "Save to Downloads" or "Save to Gallery" . This usually triggers the app to restore its original name or a more readable format.

Why Did Telegram Rename My Video? How to Fix Files Like "AgADVQwAAnO2kFY.mkv"

The .mkv extension stands for . It is a powerful "container" that can hold multiple audio tracks and subtitles. However, Telegram often struggles to play these natively, sometimes only showing a single frame of the thumbnail while the audio plays. 3. How to Properly Save and Rename