I personally do not see exposure as that big of a deal personally. Exposure through lack of practice would be a problem not because of the exposure but because the performer has not put enough time into doing the trick properly not to expose it. When it comes to exposure on purpose, has anyone ever done a trick and the person you are performing gone "Oh I know how you did that, I saw it on YouTube!"
Believe it or not, laymen do not spendtheir time on YouTube looking up how to do magic tricks. The people that would are either those who have an interest in magic (Good people) or people that are hecklers (that magicians don't like anyway) so what have we lost? Not everyone can afford to spend $30 on a single trick DVD, or may have no way to order it because of strict parenting or living in a weird country, does that mean these people should be disadvantaged?
People talk about expanding magic, but then go crazy because people aren't buying thier way in. If someone is interested enough to work out how a trick is done from a video, or find somewhere it is taught, how is that less reputable than spending $30 and getting the trick? Even laymen have money, anyone could come here, spend $30 and learn how to do a trick. The net difference? Money. If you want to expand magic you need to make it accessable to those that want it, not those that are rich enough to buy thier way in. For those that don't have the dedication, they will just spoil the magic for themselves, they will get bored knowing all the secrets, it's their loss.
I know the magicians here and everywhere work hard to make and poduce these DVD's and for that they deserve to get paid, it's great work they are doing. But I see buying a DVD as helping the artist and getting something in return rather than just buying the item for the contents. If I just wanted the contents there are hundreds of better places than YouTube to get entire magic DVD's for free.
My advice is to stop crying over exposure and spend more time developing your skills than worrying about the internet. The internet cannot be controlled, trying to is just a waste of time. Trust me.