Waiting Room Video not working

I'm trying to upload a video for the waiting room and keep getting this message: The media could not be loaded, either because the server or network failed or because the format is not supported.

The server or network has not failed, the format is mp4, the size is under 30mb. Last time I got it to finally load but then it did not play in the waiting room when the webinar went live. 

I'm working in Safari in case that's relevant. I also tried in Chrome with the same results.