There's a lot to unpack here. But just to be clear. Yes, the white truck should not be in the passing lane going that slow. Move over and let other cars pass. That being said, the driver of the Honda is absolutely at fault.
It seems like the Honda was driving erratically even before the video started. But we see the driver tailgate the white truck and eventually make his move to pass. As he does this, he sideswipes the truck and loses control cutting off the other car before flipping.
The Honda should have been a better driver, and the audio shouldn't have been happy he crashed. Hopefully everyone is okay!