It was either scripted or heavily edited. Notice for everytime someone messed up, they answered another question correctly. They probably just cherry-picked the most outrageous parts.
This is sad, but I know that me and my friends from high school, the ones in AP and advanced classes and the ones that are really part of the future leaders in our nation, could answer those without any trouble. So it's not like this is some eye-opening statistic. There have been stupid people every generation.
I wouldn't know the capital of Washington, or when the US got their independence cause I'm Canadian, and I could answer most of the others. And if it were about Canada I'd be able to answer them all. These kids