Which came first, the chicken or the egg?

The video calls it a proto-chicken. So proto-hen laid an egg, and proto-rooster fertilized it. ... So in a nutshell (or an eggshell, if you like), two birds that weren't really chickens created a chicken egg, and hence, we have an answer: The egg came first, and then it hatched a chicken. Ctto

While this is a common philosophical question, there is actually a firm answer that makes use of the theory of evolution. The answer is an egg that was laid by the immediate evolutionary ancestor to the chicken. The genetic differences between that parent and the chicken would only have been very slight. This raises a new, more philosophical question - how many genetic differences are required to define a new species?