This specific naming convention ( AgAD... ) is a unique file ID generated by Telegram.
If you still have the chat, look for a video file sent around the time this file was created. AgADtAIAAkXhEEQ.mkv
If you found this in your device's "Telegram Documents" or "Telegram Video" folder, it is likely a video that was downloaded but not explicitly "saved to gallery/downloads" with its original name. This specific naming convention ( AgAD
The .mkv extension indicates it is a Matroska Video file, which is a high-definition container format capable of holding multiple audio tracks, subtitles, and high-quality video. How to Identify the Actual Content AgADtAIAAkXhEEQ.mkv