I think I understand it the model. He knows he needs to get xyz no. of viewers (probably quite a lot) then more advertising which is easier with more views you can charge higher rates with big viewing numbers. It's a gamble of sorts but then so is every business.
If you wanted to open a shop you have to re-fit it, stock it with whatever you are selling, pay the rent/rates, bills etc. Requires quite a substantial investment and most will go to the bank for that. Then you need xyz no. of people in the door to break even and over that it's your profit. With a photo studio you have a similar issue you get more revenue with increased presence in the high street, but have costs to maintain it. One reason I think most photographers now work from home, you have low overheads your expenses bar some equipment are mostly advertising and basic stuff like phone/internet, maintaining a web presence is not costly either.
With cameradiner I think it's probably located where he lives (maybe an outdoor building or in the house) he worked at a fairly senior position in Sony so we assume he got paid well for that and got a decent redundancy so that covers the cost of the video gear and fitting out the place to shoot easily. Some folks also have multiple sources for an income it might not be the main source at the moment.
I look around and see a few people who do seem to be doing ok. Jared Polin's (
http://froknowsphoto.com/) site sells clothing and he charges for appearances at events, he has referrals for well known purchasing sites, sells DVD's with tutorials etc. I find him a bit annoying but he gets views and probably manages to live off that no problem.
Youtube can be funny at times, I see one working photographer from Australia who is doing photo reviews and thatnikonguy etc etc. Obviously he's probably not quite as busy as you might think for a working photographer (else he's not have the time to do those videos)
A college professor once told me if you can't earn a living doing something (ie photography/video or whatever) then earn one teaching people how to do it! I've seen many photographers broaden their field to try to get additional income and that is one way of doing it. But there are quite a few doing it that's the problem. I suspect DPR don't make a profit (they can't with their staff costs alone) With cameradiner it's really a numbers game for him.