You mention incorporating and in the TC comments someone mentions legal fees. I watched the video and I thought he was leaning far more towards a minimum viable

You mention incorporating and in the TC comments someone mentions legal fees. I watched the video and I thought he was leaning far more towards a minimum viable product than a fully functional site - he doesn't really talk about actually having a proper product much - more of getting to a point where you know if you have a goer or not. I don't know about in the US but in a lot of places you certainly do not have to incorporate to launch a product, or even to make money from it. I'm pretty sure technically in the United Kingdom and New Zealand (markets I have started businesses in) you can make as much money as you like without ever becoming a business. I'm sure the tax department would find it interesting if you declared 50 million revenue on your personal tax form, but no reason why you can't do it.