Alright so the issue seems to be with a windows update messing around with something. In any case, all you have to do is uninstall the update and the video's will play fine (untill microsoft fixes the bug on their end, but who knows how long that will take lol).

Step-by-step:

Start menu > Control panel > System and Security >

In the section with the windows update, the last option is "View Installed Updates", click on that one >

Copy paste this code into the search bar at the top: KB2803821 > Right click, uninstall.

KB2803821 is the specific update that is causing the issue (and the issue is affecting other programs as well such as adobe premiere).