It strikes me as odd that so many people think a business has to be unique to succeed. 99% of businesses do something that another business already does. For that matter, almost by definition, most businesses are not the leader in their niche. That doesn't make them unprofitable.
I understand you're joking, but I guess that depends if you are trying to monopolize a market, retain first-mover advantage, etc. I guess ability to execute is itself a type of moat, perhaps especially so when the potential competition would be other startups that are statistically highly likely to fail.
Still, I wonder how many head-on competing businesses of a particular category the market can bear before they start feeling it via competitive pricing pressure, lower sales and/or slower growth, etc. What if there were 2 more video-flipbook companies, or 10 more ?