"Sea Forest Waterway", the competition venue for Olympics, Canoe (Sprint) and Rowing ,and Paralympics, Canoe and Rowing for the Tokyo 2020 Games, was completed in May 2019. The footage was put together by pictures taken from the stationary camera fixed on the Tokyo Gate Bridge. The photos were taken from December 2016 until the construction was completed.
You can see the bicycle path being constructed which is like a whitel line extended from the centre of the screen toward the end, and also the situtaion of the dams moving slowly from either side.