I see that some folks root prune every few years.  Regardless the pot size, I find that it's necessary to root prune every year to maximize growth potential. 
If you root prune every 2-3 years, are you getting a lot of growth on the 2nd-3rd year with this practice?

See http://figs4fun.com/bills_figs.html

Are you still using all 5 gallon buckets like in your Youtube video?  I'm doing the same for my trees and I cant imagine not root pruning every winter.  They grow so fast.  

Just thinking!
if using light soil the roots outgrow it so fast that its necessary.

Roots in heavier and nutrient dense soil like full compost like bill us using probably take more time.

Still learning the ropes myself

Regardless of the soil medium you are using, I think that root pruning is beneficial to the plant. I only have limited experience with this practice, but after a couple of years it is safe to say that root pruned trees are simply more vigirous.