Its a common issue. The video which you downloaded will get sorted in the order of date in which its created(if the creation date is available in the video).
Anyway try wiping your cache partition. It's recommended after major updates. (Switch off your phone. Press and hold, power button and volume-up button for 4-5 seconds till the phone turn on and boot into the recovery mode. Use volume keys to navigate to 'wipe cache partition.' Use power key to select and confirm. Then reboot your device. Normally, this will not effect any personal data or settings). Thank you.
