I like the tutorial too, it is about what I understand under high-key photography nowadays.
For a tutorial I miss the historical background. Back in the black and white days in Hollywood they used to place the key light high for the good guys, while they lite the wretches from below. This is where the terms come from, though the interpretation in photography nowadays is something else
Another non-tech question. When do you use high-key (besides brides

)? What are your associations with high-key?