Hello,
It seems you are with the default image installed, and if i recall correctly that was Beta1 with Phosh.
I would suggest to try and update, eventually edit /etc/pacman-mirrors.conf and modify the Branch line to be like this:
Branch = arm-testing
then run from terminal:
sudo pacman-mirrors -f && sudo pacman -Syyu
The password is the PIN code 123456
Reboot the phone once that is done. It might give you some troubles at reboot and you might have to turn it off and on again. After that try again to play the videos.
In case of failure, use Jumpdrive to be able to flash the img on the eMMC
See here more detailed instructions for that
https://wiki.pine64.org/index.php/PinePhone_Installation_Instructions
Get the latest img from here