Virgil - Is DDA looking to provide learning latin dance online?
Our goal is to allow each dancer to experience the elements of dance; confidence, creativity, grace, musicality, rhythm, technique, an appreciation for music and dance and above all fun!
I'd agree with Sweavo - in that there's no subsitute for the personal attention of a good teacher.
If you can't easily find a good teacher, then it's a fall back, aide memoire, though not a total alternative - those wanting to learn salsa are likely going to go to a class(es) prior to doing social salsa dancing.
So i'd say it depends. What is the learning wanting to be done? How well known the instructor is, isn't a factor necessarily in how well they can help people instruct via the web.
You've got to take into account their strategy to teach people, their content, their video quality, video resolution, accessibility of materials, accurateness of materials; scope, breadth and relevance of materials.
It would be interesting to go on figures, rather than hunches, that the majority of learners do a lesson, rather than online learning, and that even given the choice, the majority would prefer a social lesson over online learning.
Video is a good supplement as Sweavo says - not so good as a full replacement for all training and learning. It in some ways has relevance right at the start, then once the dancer's got the foundations checked by a decent teacher. (Not to say that that couldn't be done online! - It's just less common - lessons give a one to many participation - one teacher, many students. Much harder to set up a one to many with online tools (and thus effects on costs).
As barrefly mentions - the physical touch to correct position is useful at the start - it helps cement the muscle memory of both postures and movements.
For the absolute beginner, it could help alleviate that brainfreeze, trying to link foot movement to music, to beat, to hand movement to name of the salsa move - it can be very overwhelming initially! There are already resources for that, for a dollar or two, and even free - your mileage may vary.