Sure, strictly speaking I consider mathematics to also be philosophy, so in general philosophy is not useless. However, common philosophy tends to be useless, including the lecture that was submitted here. I think if somebody wants to really learn to think precisely, they'll study maths. So most philosophers are "just" faking it by making too many words, hiding the fact that they don't really have a clue. Sorry if that sounds arrogant, I have just been so consistently been disappointed by popular philosophers.

Note: I have studied maths myself. I am no Gauss or Erdös, but I guess I have my standards for the application of logic, and most of the time, philosophers don't meet them.