We've recently updated our video player, and this has caused issues for a handful of students. However, you can now switch back to the old video player if you'd like. You can do this by clicking on the 'Profile' tab at the top of the page. Scroll down your profile and click "Edit Account and Profile Info." On the next page, you'll see the option "Use alternate video player" under 'Settings.' Simply click on that, and the problem should be fixed!
Thanks for your patience.