fixed some bugs due to optionals
fixed some bugs due to optionals

Could cause crashing on the VideoViewController if the user pressed
menu (back) before the video started streaming

StreamCenter/StreamCenter,OlivierBoucher/StreamCenter,chayelheinsen/GamingStreams-tvOS-App,OlivierBoucher/StreamCenter,StreamCenter/StreamCenter,chayelheinsen/GamingStreams-tvOS-App