1. Low Resolution is selectedMake sure the video settings is at the highest resolution.
You can check by clicking the gear icon at the bottom right of the video. It will give you a video quality selection. The higher the number, the higher the resolution so choose the highest number.
This works for both free and premium videos.
2. Video has just started loading.All streaming videos can start off in a low quality version and adjusts to a higher quality after a few seconds. After ensuring that you've selected the highest resolution, best to wait until it loads.
Note: If you're still having trouble with the video after performing these two solutions, consider downloading the videos.
For instructions on how to download the premium videos, contact Customer Support