Tutorial Videos - Access Denied

I've been using the WP tutorial videos on a site for some time now, but recently they've changed to show "access denied". I can see that the domain is still registered, so that's not the problem. I recently put my site onto https:// from http:// so I'm not sure if that could cause a problem?

You can see an example page here:

It's a free course, so you can register to see the page.