This problem has long been a problem for me and I have searched everywhere for a solution but, unfortunately I have not. To be concise I have a application that downloads YouTube videos and also has a web view to display web content. When viewing videos however on YouTube and the HTML5 player is being used when you press the fullscreen button, nothing happens :-( I have tried the same thing with Safari and it goes to fullscreen when using HTML5. Can someone please help?