The Zambezi runs on the border of Zambia and Zimbabwe, and 100,000 CFS is considered to be low water there. It runs, I have been told, as high as a million CFS. They say in the video that it's high water, but not how high.
Here's a blog with good info and pictures of the Zambezi. I only know of it because some guides I have worked with also worked there. I have no intention of going to run this whitewater. I prefer little creeks and lower risk.