GamePress Video Thumbnails

So I have this small issue with the videos portion of the GamePress theme. I can post a video no problem, just use an iFrame in the Text tab of the main editor and all is well. However, when I go to the Videos page which lists (obviously) all of my videos, I have instead of an actual thumbnail a red image with the words video thumb placeholder 284×158. Is there something I need to do to get an actual thumbnail, or will this resolve itself over time? Tried the URL, iFrame, and object methods.
Image of the problem.
Webpage in question.