I watched it and here's my comments:
60%~high humidity with a dry substrate and good ventilation doesn't promote bad bacteria. It's stagnant air and poor ventilation and damp stuff in the enclosure that causes problems. You know the humidity in Ghana where ball pythons are native is constantly 70~90% or more throughout the year.
He never once brought up his actual humidity in his snake room. Depending on where he lives, perhaps the humidity in his home is 40~50% anyway, and that's still within decent range outside of shedding, where I assume he adds a humid hide. But your 10% humidity is extremely low, and it's always best to provide known and proven good care, IMO at least 40% humidity in the enclosure, than to experiment with a life.
If he doesn't provide humid hides AND doesn't pay attention to humidity, I guarantee you the humidity in his home is at least 60% and lucky him just doesn't realize it. If you haven't seen a ball python have a poor shed yet, they always will at around 50% or lower humidity if they don't have a humid hide/hole. That's just what happens to them.
There's no real evidence that low humidity causes RI though, even though it's speculated.