Is anyone in this group selling educational videos via a hosting website (in my case Expertise TV)?
I am not, but I am involved with a streaming TV series which is distributed online.  In general, online distribution channels are worth it for the accessibility and ease of use it brings you.  

There is always the risk of people pirating your work, but that risk exists even if you never put things online.  If you distribute DVDs, there is nothing stopping someone from ripping them and posting the content online.  If your platform of choice employs DRM, then it provides at least a minimal barrier to copying the content online trivially (though determined people will still manage to do it, but they'll succeed regardless of distribution channel).

If you currently only do live events and are wondering if video is worth it vs just doing live events, that's a little more tricky as a much more limited group of people would have the opportunity to film you with their phone and post it (and the quality would be substandard at best for such videos) but if you are already recording your lectures, then online distribution carries a lot of benefit for the risk involved.