That was a very good overview about ND filters and I agree with everything he said. I've been a commercial photographer for 30-years and ND filters are a pros secret weapon.
I have one added comment, I agree you need an ND32 and I've found, really an ND64. Here's my tip. Don't buy the cheapest ND filters you find. I did that twice and both times the 32ND density was about 1.5 stops too light. While cheap filters will work and will have an effect on your images and footage that might be helpful, if you truly need the density of ND64 to knock your video shutter speed back to 1/30th, then you won't be able to achieve that with a filter that is not the correct density.
After ignoring my own best judgment and saying "I'm sure the cheap filters are fine" and then finding that in both cases they were not, I bought PolarPro. They are expensive but after doing measurements, they are right on density.