Vidly is building on Twitter in the same way Micro-soft (as it was then called) was building on the Altair.

So sure, Vidly could IPO. Their path from here to there would be as tortuous as Microsoft's, but all the best companies are transformed as they grow. All you need initially is a starting point, to engage with users.

You are in effect framing the question as "could Vidly, without writing another line of code, have a successful outcome?" Probably not, but that's not the question that matters. The question that matters is "could Vidly, starting from this point, have a successful outcome?" The answer to that is, of course they could; any point where you've made something people want is probably good enough, barring certain pathological exceptions.

When you and the TechCrunch trolls make fun of startups launching their initial version, you're like someone making fun of Dell when it was just Michael Dell assembling computers, or Microsoft when it was just a pair of undergrads writing a Basic interpreter. How could such companies possibly grow huge?