I'm just putting a few things that I think address the shape of the earth in respectable ways, just in case I decide I want to weigh in sometime.
This first video is one in which the presenter is doing an experiment which would demonstrate the specific geometric relationships between three points of know relationships to a calm flat body of water. This is a crucial piece of information because it determines a starting point for then gathering other information to determine the overall shape. I have been disappointed with other videos for being too cavalier about measuring the specific relationship of the camera to the water's surface.
I take this experiment to establish clearly that three points that are all exactly the same distance from the surface of calm water would not be in a straight line, thus the earth cannot be concave nor flat. The earth must be some kind of concave shape in which about 50 millimeters per half mile of curvature.