A free app for Android, by GaramChat.

With Full Movie Video Player 2.0, you will be able to enjoy longer and more fun movie marathons. This convenient application supports playback of most file formats, including but not limited to MP4, MKV, MOV, 3GP, RMVB, AVI. You will never miss any minute detail on-screen, too, as it plays videos in full high definition, 1080P, and 4K modes.

The app detects the playable files in your local storage automatically, so all you have to do is grab a bowl of your favorite snacks, a handful of drinks, and copies of what you want to watch. Full Movie Video Player 2.0 will take care of the rest!