Allow HTML5 video to enter full screen mode in webview

I have a very simple test version of the application. All he does is show a web view and upload a Youtube video page. Loading the page and playing the video is all right, but clicking on the full-screen link does not affect. (see screenshot below). I checked that if the video is played using a full-screen Flash player, everything works fine, but HTML5 full-screen mode does not work. Are there any delegate calls or other workarounds that may include full-screen HTML5 video in Webview?

#import "AppDelegate.h"

@interface AppDelegate()
@property (weak) IBOutlet WebView *webview;
@end

@implementation AppDelegate

- (void)applicationDidFinishLaunching:(NSNotification *)notification {
    NSString *url = @"http://www.youtube.com/embed/VCERs0v1OoI?html5=1";
    self.webview.mainFrameURL = url;
}

@end