UIWebView Youtube在iOS 3.2(iPad)中嵌入声音播放,但没有视频显示

这是我正在使用的代码:

UIWebView* webView = [[UIWebView alloc] initWithFrame: CGRectMake(0,0,320,480)];
NSURL *url = [NSURL URLWithString:@"http://url.to.video/"];
NSURLRequest *request = [NSURLRequest requestWithURL:url];
[webView loadRequest:request];

VideoPlayerController* videoController = [[VideoPlayerController alloc] init];
[[videoController view] addSubview:webView];
UINavigationController*  theNavController = [[UINavigationController alloc]

initWithRootViewController:videoController];
[self presentModalViewController:theNavController animated:YES];

[videoController release];
[theNavController release];
[webView release];