Thanks for posting this link Pap rika
This is really interesting. I've just watched the base gravy video (for the first time) and from this and the comments there is already some really good points to consider and discuss. I'll be watching his other offerings at some time in the near future. Now I don't know whether to do his base gravy or the KD for my next batch. Maybe I just have to make 2 small batches or eat a lot of curry. ;D
Notice the can of East End Pure Butter Ghee and also in the comments when asked which Curry Powder the answer is East End. Best quality. (unavailable to me)

Cream in the Base Gravy and he says he can use it for a Korma, a Madras and a Vindaloo for example.
The oil content of 1 full cup and cooking to separation point. No removal.
He cooks 4 litres, adds extra water to a very thin base and says it could make 6 - 10 then corrects to 6 - 8 curries. Even at 10 he's looking at near 500 ml per curry. This again draws me to the conclusion that BIR is much wetter than AIR.
Take note of this one Phil. He specifically points out the requirement to allow it to cool before putting it into a stand blender. ;D
The point that really says something to me is his comments about why base gravy is used for expediency only and that it is much preferred to cook "traditionally".