I believe I may be able to help you out. Down in the bottom right hand corner of the player there should be a feature titled "Aspect". Next to that is a little button titled "Zoom". If you click on zoom you can change the format of the video. As you click on this button, you will notice that the letter next to the word zoom will change. You will most likely want to choose "A" depending on your computer screen. Try each of these options and check for the best format by viewing each setting in "Full Screen" mode. Here is an article that explains how to do so. Changing Aspect Ration (Video Zoom)
I hope this helps!
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