Oleg,
In terms of the initial startup flames I think you have the perfect colour already, no more red required.
I attach comparison shots from the previously posted P-51 Old Crow startup against the flames in your video. You have them spot on I think.
Once the engine is running it looks like red/blue is the expected colour though. I haven't seen any yellow flames from a running engine yet and the colour chart previously posted only mentions yellow flames when the spark plugs are defective.
Would be nice to occasionally see the large lazy flames caused by an overpriming stack fire too.
Thanks