Substitute Image Not Showing on Mobile Devices

[yetiracing4als]

We have noticed bug with background videos that seems to be unique to the Cascade template. On mobile devices, the substitute images don't show up in place of the videos. Instead, it says "Sorry, this content is not accessible." I've confirmed this on actual android and apple devices, and it's reflected in Chrome's mobile device simulations as well. Here are test URL's showing the behavior:

Used an iPhone and navigated to the "Why Is Petrified Forest a Great Place to Study Birds?" section: http://www.arcgis.com/apps/Cascade/index.html?appid=0e0b07b70d4c4c16b320a34495fa64ce