This is a result of your DOM container being too wide to look good. If you look in your tubepress.css file for ".content .container .container_inner" these are the elements making it look bad.
Sorry for the wrong information above, thought you were on the newer version, not 3.1.6. By the way, you will want to update sooner rather than later as YouTube is turning their API v2 off within the next 30 days!
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