There are 3 main Physics Principles behind Siphon Generation:
Hydro Static Pressure
Pull of Gravity
A siphon works because gravity pulling down on the taller column of liquid causes reduced pressure at the top of the siphon (formally, hydrostatic pressure). This reduced pressure means gravity pulling down on the shorter column of liquid is not sufficient to keep the liquid stationary so it flows from the upper reservoir, up and over the top of the siphon.
When the crest of a wave is at the first vertical intake pipe the water level will be higher at that pipe than any other vertical intake pipe, thus the water will start flowing up the first vertical pipe at the crest of the wave. The one way valves in the other intake pipes would prevent the water from flowing out thus forcing the water to flow through the horizontal generating pipe turning the prop and generator, thus producing electricity. The water would then flow down any of the exhaust pipes in which the water height outside the exhaust pipe is below the height of the water outside the first intake pipe due to the siphon effect.
When the crest of the wave moves to the second intake pipe the water level is higher at the this pipe than any other intake pipe causing the water to flow up this pipe through the horizontal pipe turning the generator in the same direction, generating electricity and flowing down the exhaust pipe closest to the trough of the wave due to the siphon effect.
The valves in the intake and exhaust pipes would jointly cause the water to flow in only one direction through the horizontal pipe, from the intake side to the exhaust side. This would cause the generator to turn in only one direction.
After you pour a little water into each bucket you then get the air out of the tubing priming the system. Then, when you pour more water into one bucket it'll siphon over to the other bucket, spinning the turbine, until the levels equalize. Then you've got to pour more water into one bucket to get the siphon action started again. Once both buckets are filled up you've got to get rid of enough water to make more room in the buckets.