I have spent some time in the evenings this past month or so watching a lot of ski instruction videos, including pretty much every one listed in this thread. I love watching the Ballou and Beaulieu, as they make everything look so effortless, and enjoy Josh Foster's super-positive and relaxed attitude. Can't say that I have not also enjoyed and benefited from watching some of Harald Harb's videos as well. For the complete package, however, the Ski School by Elate Media is nice as it is full of drills and folks like my wife, who has only been on skis for a couple of years, can see the future, so to speak, through the nice progressive sequence, and she has also fallen in love with Lito Tejada-Flores Part 3, and his corny yet sincere meditation on 'Why we love skiing'.
I have also recently stumbled upon the Warren Smith Ski Academy, which is also shows a nice progression and tackles things like strategy off-piste, that I find helpful.
Started watching the Avoriaz ski school last night, between innings in the baseball game, and it seems to have potential as well.
I know that none of this beats taking lessons, but watching these videos is a great way to get tips from a wide range of experts, all of whom focus on slightly different aspects of the same things (edging, balance, fore-aft movement, etc.), have their own unique style, and often provide me with little epiphanies about things that I ought to do a little differently.