James the point he is making is that the US should of armed and trained the FSA when they were the strongest rebel movement, and iSIS and JN etc were not much of a force.
The USA did arm and train the moderate Syrian rebel groups, despite public statements to the contrary, it hasn't made much difference, and a lot of those "moderate" groups later defected to ISIS anyways, making the whole exercise pointless.
Also for every dollar the USA sent, Russia and Iran sent 10 dollars and their own special forces, and Gulf Arabs sent 20 dollars to ISIS. The more involved the USA gets, the more money people will send to ISIS, the more involved Iran will get. In this game, the winning move is not to play.