i watched a video about bike fits, and one of the things they said, once in position of riding, when looking down , the front wheel's hub should not show, and the handle bar should cover the sight of the hub, is this true ?
No, we are all different.
If you watch the pro tours, you'll see some on bikes that look too large and others that look too small and their head completely past that sight line. And the Goldilocks' on on bikes that seem just right don't win any more than the others that I've noticed.
And they ride a lot further, faster and longer than I do. I'd think they'd demand the same comfort that I do.