Researchers Sweller and Cooper looked first at the teaching of algebra. Early on, they saw that merely showing worked problems was not any better, learning-wise, than merely having students solve problems on their own. With sufficient structuring, however, which reduces cognitive load, the method appeared to work better than unaided solutions. Importantly, for media designers, they found that (paper) display of both text and diagrams reduced cogntive load, as we covered in an earlier post (Split-attention effect). Sweller later proposed applications for animation, (closer to home for us).
Not for beginners
The folks this strategy works best for are the more experienced students, and just a little "worked" material seems to be sufficient, follwed by multiple experiences of unaided solving. All of this is related to a more general body of thought, coming out of Dewey, Piaget, Montessori, Vygotsky, and others, called Problem-based learning (PBL) where students collaboratively solve problems and discuss their experiences as they go, or immediately following the exercise.This is not a matter of dumping the non-swimmers into the deep end. PBL assumes some earlier, didactic training in various problem solving strategies and heuristic reasoning first. In this view, the teacher's role quickly shifts however, after providing sufficient theorectical and procedural structure, to that of a facilitator of active collaboration by students facing a challenging, practical problem. The payoff is solving in context, with the complexity of the real-world reflected in the process as well as the outcome.
This techniqie has been applied extensively in professional training for physicians and engineers, and is one I'm entertaining for the training of non-profit professionals in recruiting, fund-raising and enrollment tasks.
Most of the citations I've found are in classroom or lab settings. Applying the technique to video and online will take some imagination. Clearly, the media will have to model a process as well as introduce specific "challenge" materials to be solved.