Video File mode - .AVI & .MKV support?

Hello! So, the bug with the loading of the file itself has apparently recently been fixed, but I have noticed that the Video File mode can only play .mp4 videos. When I choose .avi or .mkv videos, the player loads and so do the subtitles, but the video itself won’t play, the screen just remains black. With some .mkv files, though, there’s sound, but no image. Is it a bug or are only .mp4 files supported so far?