I keep hearing people saying that, and frankly feel kind of stupid for having no idea what they're talking about. Other than the revelation that you-know-who* overheard you-know-what being predicted all those years ago, just what was skipped exactly? Oh, that, and a big noisy battle scene. Frankly, I'm so blown away that a modern filmmaker actually chose to foregoa big noisy battle scene to spend more time on character development, that I don't mind a bit. But the crucial bit of info that seems to have been skipped - why, it would take 10 seconds in the next movie to reveal the same piece of info. It didn't even come from you-know-the-one, may he or she rest in peace; it came from that other person who sort of faded into the background before the final sequence.
And HP is an excellent example of secret history.
*not the You Know Who, mind you - the other one.