The best lesson to take from all this is time.
Look how much time goes by from the very start of things going wrong, to when the car hits the debris. It seems like a long time, and maybe he decided not to react, but t shows us some things.
First, we're watching a video knowing something bad is about to happen, so we're watching for it. The driver wasn't, he was just cruising down the road oblivious to what was to come. No reason he should have expected it.
Second, at whatever point he first notices something is going wrong, a second or two is not a lot of time. Reaction times are seriously longer than what a lot of drivers like to think they'd have.
Finally, whether he meant to or not, he did the right thing. Most times driving through the debris is the safer thing to do. Yes, you'll likely incur some damage (and I bet he did), but swerving to avoid it would likely involve hitting other vehicles. People also tend to over react when swerving and crash anyway, often with more severe damage than had they not.
As far as the pop up goes, I can only guess that it wasn't latched. Having towed many pop ups, I can't see how wind can get under the roof without the latch being left open or damaged in some way. Also, it kind of looks like the trailer is swaying a bit a few seconds before it went high order. Anyone else see that? Watched on my cell phone so I'm not sure. If it was, I'd emphasize that when your trailer starts acting funny, it's time to slow down and get off the road to investigate.
