I've commented a couple of times in this thread and as a Penn Stater it's all very hard to digest, but if nobody has given some more context on McQueary I think I should. I have not read this entire thread so please forgive me if it has been mentioned and this in no way is defending him or his actions (or lack thereof) but may give you some insight into his perspective.
McQueary grew up in State College and went through the school system there. He grew up with several of Sandusky's adopted children and knew the man since he was a boy. I'm pretty sure he had sleepovers at the house sometimes like some others in this thread and in the media have mentioned, but I'm not sure. Their Dad's are friends and from most accounts nobody ever suspected anything like this was going on until the incidents reported in the GJ indictment. He played QB at Penn State through 1997 and then became a graduate assistant which he was doing in 2002 when this happened. So, rather than just assuming that he was just walking in on some random guy or even some guy he just knew of doing this horrific act, put it into the context that this was a known and (unfortunately) trusted person/family friend who was committing the crime. Would you not be shocked? How do you know how you would respond? I would like to think that I would do what all the internet commentators are saying and beat the hell out of the guy, but I honestly don't know. This in no way excuses the lack of action, but might give some perspective as to why this wasn't so cut and dry as to how to respond.