Looking at the video again, it seems more like a tip rather than a somewhat constructed method. A simple digital camera is not really a good term to use, it makes it seem like anyone with a $50 camera could get in this niche. He is also making it seem like just anyone could get a great single image that sells thousands, most people will probably get around 5-10 sales a year of an image if that. That is why you need to build up at least a 10,000 image catalog(imho, it may be overboard) and consider it a full time career and not just a hobby.
If I was interested in getting in this niche I would at least get a DSLR camera like this, its not even a high end but it should do for getting started in the niche. Later on I would go out and reinvest some into a better DSLR camera.
http://www.bestbuy.com/site/canon-eos-rebel-t5-dslr-camera-with-18-55mm-and-75-300mm-lenses-black/1004002.p?id=1219459331617&skuId=1004002
Even shooting 500 images a day, it would be close to a year before you would use up 1TB of storage. So you can pretty much build up a catalog very fast with the best images and with the lower quality images you can use it for a personal photoblog.