Just a question?? Perhaps it is only a perspective issue from the video, but your koi look almost stunted...not all but some. They certainly look happy, gorgeously colored, and very well fed but seem to be too thick in comparison to their length? Edit...as I look at the video again perhaps obese might be a better term than stunted....
Is it just an illusion? Certainly not trying to be insulting or critical in any way...just curious!
Fyi...longtime koi keeper and previous retailer of quality imported fish(more than 25 years ago).