Just tested your code, it works fine on an iPhone, Youtube videos are not supported on the iOS simulator though, so you'll need a real device for testing.
How can I position this box?
You are already passing the X (20), Y(20), width(100) and height(100) of the box at this line:
[self embedYouTube:@"http://..." frame:CGRectMake(20, 20, 100, 100)];
To change the position of the view afterwards, you modify its center property:
videoView.center = CGPointMake(200, 100 );
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