What would you say consider to be "blackbelt techniques"? Is there really such a thing? Or is it that "fancy" moves are called blackbelt techniques because of the difficulty involved in their proper execution? Or is the identification of certain techniques as "blackbelt techniques" simply a marketing ploy to sell instructional books and videos/DVDs?
IMO, blackbelt techniques are the same as white, blue, purple, and brown techniques. They're just a lot more refined and with better timing.
Definitely marketing.
I generally agree with the above sentiments, although I think that there is such a thing as 'fundamental' and 'advanced' techniques, 'fundamental' and 'advanced' setups, and 'fundamental' and 'advanced' counters/recounters.
A 'fundamental' technique might be the leg on shoulder guard pass - everyone uses it, black belts just use it better. An example of an 'advanced' technique might be the jump-spinning toehold.
RoninGear is correct!