High-quality MKV files of documentaries or educational content are often available from legitimate sources like university archives, NGOs, or the BBC, per the Alibaba insights on MKV movies .
MKV files are versatile, but they require appropriate media players: Download CamYChi mkv
If you need to convert an MKV file to a more compatible format (like MP4), you can use these tools: Provides an online MKV-to-MP4 converter. or the BBC