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Go to Settings>About Phone, and tap on Build Number seven times. This will activate the Developer Options. Tap the Back button once, then look in the main Settings menu for Developer Options. Tap it, and see if you can find an option to switch between NuPlayer and AwesomePlayer. If there is an option, then switch it from whatever it's on currently to the other setting (i.e., if it's set to NuPlayer, switch it to AwesomePlayer, or vice-versa).
(BTW, "toggle" means to switch something from its current setting to its other setting.)
If you're only having problems with the videos you take with the phone, though, I don't think this will help. You're taking the videos with the Camera app that came with the phone, right? In other words, you didn't install a different camera app and use that instead?