iOS: Playing video that needs authentication works in QuickLook but not in MPMoviePlayerViewController

I login to my server using a SOAP web service. Once logged in, many of the files that I am viewing are only available to the logged in user, so iOS must create a session in NSURL or something.

When trying to preview a video file using MPMoviePlayerViewController it will not work, it just loads up the viewController, then dismisses it.

If I use QuickLook it does work, probably because I download the video locally first, then view it.

But, I don't want to do it this way, I want to stream the video using MPMoviePlayerViewController because I don't want the user to have to download an entire video file. I have seen posts about using NSURLCredential but that doesn't seem to work for me. I used (added my own personal info obviously):

/**
 * Play media session
 *
 * @version $Revision: 0.1
 */
- (void)playMediaWithURL:(NSString *)mediaURL {

    // Authenticate
    NSURLCredential *credential = [NSURLCredential credentialWithUser:@"myusername"
                                                             password:@"mypassword"
                                                          persistence:NSURLCredentialPersistenceForSession];

    NSURLProtectionSpace *protectionSpace = [[NSURLProtectionSpace alloc]
                                             initWithHost:@"mysite.com"
                                             port:80
                                             protocol:@"http"
                                             realm:nil
                                             authenticationMethod:NSURLAuthenticationMethodDefault];

    [[NSURLCredentialStorage sharedCredentialStorage] setDefaultCredential:credential forProtectionSpace:protectionSpace];

    // The movie player
    NSURL *movieURL = [NSURL URLWithString:[mediaURL stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]];
    MPMoviePlayerViewController *tempPlayer