It's a firewall/ad blocking issue. Because you have placed the image files in a folder with a name that appears to refer to advertising (promos), some ad blocking software, such as Norton Internet Security, will block your images from displaying. When I crank up my ad block settings in NIS, I see just what folks are describing.
In order to avoid this, people are either going to have to disable any ad blocking features associated with their web browsers or you're going to have to move the clickable image files to a URL that doesn't contain words like promo, ad, banners, etc.
The easiest option, however, would probably be to make the promo titles underneath the clickable screen grabs also link to the videos.