You can check the hash against security databases like VirusTotal or Cisco Talos to see if it is recognized as a known safe file or a piece of malware.
Since the filename is a hash, it is often used by automated systems or private archives. You can verify what the file actually is using these methods: 90eac71c5649883967e5a706b937f58c.mkv
Use a tool like MediaInfo or the ffprobe command to see the internal metadata (resolution, frame rate, audio tracks) without fully opening the video. You can check the hash against security databases