I tried it by hand and software too, I bought even a mouse what looks like and is used as a pen (but needs no pad). You have to get used of it, not so easy.
I was astonished about the online colorizer/calculator, how far they are now even in a free demo program. Remember the first tries years ago on old war pictures weren't looking so good.
I think 'made by hand' like in the video will always look better than just calculated.