That was a cool video, but when you watch it you will see it is that the color she used is a high lift color with 30 volume. The lightening agent in it is very strong to lighten darker hair. The process is not a typical 2 step bleaching/toning ritual.
The girl seems to know her stuff and recommends toning the ends with something non-damaging when doing regrowth.. very good advice!
I did find it unusual though, that she got the desired effect when she re-did the darker parts of her hair that were previously coloured... usually using color twice on an area won't lighten it more... but I suppose because it is high lift type colour, it did work.. good for her!