Pornotube isn't the problem. It's sites like rapidshare and limewire that are the places where people are downloading pirated content.

That being said there still is an overabundance of porn out there and when you get right down to it there isn't anything new and original that would make people want to go out and buy it. At least not at the rate of consumption in the past. Remember, there is only so many holes that a woman has that can take dick so eventually it's going to be boring to a lot of people. And despite the best efforts of the fine people at JM and Chez Max to come up with different product their audience is significantly smaller than the porn viewing audience at large. Therefore struggles will continue.