you can shut it off in options Options>Theater view>Appearance>Theme>Online media show (not easy to find^^)
not terribly quick though - you could create a zone with one config with it on and the other off. You could also create a second theme from the default as a copy, again one without the slideshow and one with - you could toggle between them but you would have to go throught options in standard view.
Using zones would be better I think