In this clip, the angler makes a few casts but they all have micro-drag. Drag = flies being towed slightly faster than the current in which the fish are feeding. By raising the rod a little higher and stripping in a bit of fly line he reduces the surface area of leader and tippet contacting the water which creates a slightly slower presentation. First cast with no drag and he has a fish. A small Trout, but still a fish.
Improperly fishing the right flies will bring a day with little result. Present your offerings the same way the natural insects would drift and the fish will do the rest of the work.