Orion player is a lightweight and easy to use video player, and it does not consume many requirements.
Keyboard shortcuts:
F11 (full screen mode)
Arrow left (Rewind)
Arrow right (Forward)
R (Refresh the player if it does not respond correctly)
Space key (Play/Pause)
You can be used as the default player for "MKV,MP4 and WEBM" files.
(Linux)
Note: This version was tested and compiled on Ubuntu 20.04 (64bits) so the app will only run on x64 architectures.