This guy is an idiot. He should have avoided the entire area if he had controllability issues. When doing demos we planned for outs in case we weren't going to safely make it to the designated LZ. Always refresh on your EPs before going up, just like flying.
Additionally, if you have controllability issues, you chop it. Once you open, 3 big questions... is it there... is it square and can I control it. There is no reason to take a non-controllable canopy all the way down.
When jumping a flag, it is possible to get it stuck in your steering lines, this can induce a turn and can change your AOA/descent rate. Best way to counter it is to use your rear risers. Now, they didn't say how many jumps this guy had, but that is pretty basic.