SLOW MOTION SCIENCE!  Ferrofluid dropping on magnet

Actually the second tide come from the centrifugal force of the earth orbiting the moon.

Since the center of mass of the earth-moon system is offset from the center of the earth, the planet actually wobbles as the moon goes around it.

This also explains why both tides are the same -- on the center of the earth (or at the poles) you are as attracted to the moon as you are pushed away from it by centrifugal force. This state of equilibrium is what lets bodies orbit each other. If you think about it, you are not moving relative to the moon so the force of attraction should be cancelled out by something, right? But then as you move away from the center of the earth, two things can happen.Going towards the moon gets you closer to both the earth-moon center of mass , reducing centrifugal force, and closer to the moon iself, increasing the gravitational pull, creating the high tide described in this video. 

The second case is going away from the moon, thus farther from the earth-moon center of mass, where the centrifugal force increases and the gravitational pull from the moon decreases, causing the second tide.

This explanation is mostly missing from textbooks as we learn about tides before learning about centrifugal force and center of mass, but a video about it would be welcome! :)