Restarting the device you are using typically solves 98% of video issues our users experience.
If that does not solve your issue, below is more information to help trouble shoot:
Occasionally we come across compatibility issues with the video player and particular graphics cards. If this happens right-click on the video player, select Settings and disable hardware acceleration.
Since video files are typically large, they do require more Internet speed or bandwidth at any given time to display the video properly on your device without interruption. It's now common to have many devices connected to the internet at once.
Your home router may only be meant to handle a few devices at once and can get quickly overloaded if phones, tablets, laptops, desktops and smart TVs are connected to one router.
You should make sure that you have a router that is equipped to handle heavy traffic if you are in a household or on a network that consumes a lot of data.
If you're still seeing issues, please submit a support ticket (firstname.lastname@example.org) and we'll give you a hand.