Now that 4.0 is public, I can edit this question and ask it again. This code works in 3.2 and any prior versions, but in 4.0 I get an alertView saying "This movie could not be played".
ivar webView
//in viewDidLoad
self.webView = [[UIWebView alloc] initWithFrame:[[UIScreen mainScreen] applicationFrame]];
webView.scalesPageToFit = YES;
webView.delegate = self;
// in tableView didSelectRowAtIndexPath
// url contains a video from web
NSURL *url = [NSURL URLWithString:@"http://www.somevalid.td/validmovie.mp4"];
[webView loadRequest:[NSURLRequest requestWithURL:url]];
In the log it says "setting movie path (null)"