I think it is a far more valid statement to say that demographics who use Hulu are a subset of the demographics advertisers will pay to interrupt with their message, probably enough of a subset that some advertisers just won't bother to advertise as at all.

However, targeting certain demographics by way of traditional advertising, like paying to interrupt everyone watching a broadcast television station, can suck as bad or worse, depending on the demographic.

As far as I can think of, it comes down to a couple of decisions: how much do you believe the medium, and not just the content, is going to affect the number of hits you get; and, how much is the feedback data you gather from your medium going to help your advertising campaign become more successful. There may be fewer people on Hulu, but your television does not provide a "thumbs-up" button at a per advertisement granularity.

So, while I think that the metrics would be bogus for trying to get a representative sample of a collective demographic who might watch motion video on any medium, I also don't think there is no worthwhile demographic information to be gleaned from posting one's media content on Hulu. It feels like a game of tradeoffs, and one you can probably only make an informed decision on by doing test runs, and seeing what data comes back.

Hopefully, this doesn't seem too pedantic; I just thought your assertion was too broad.