It all makes sense now... Yes.... Yes... it is all becoming quite clear... I know what I must do *proceeds to run out of room screaming 'ALL I KNOW IS LIES!'*
At 1:23: "The equatorial speed of earth's rotation is around 1000 miles per hour; this is faster than the speed of sound, so someone standing east of you would never hear you." I think that pretty accurately depicts a Flat Earther's scientific knowledge. What if I told you that air around you isn't stationary; it's moving with us as we spin, so your sound waves move relative to us, not in reference to static locations. That's something I expect most to know by about grade 6 science. That, of course, being the most hilarious of the rest of the nonsense in the video. In every case it can be debunked with a sub-high school level of scientific understanding. I'm fairly certain there are a small group of flat earthers who genuinely believe the earth is flat, but the vast majority are there just to troll and piss the world off.
I think I read somewhere that the flat-earther movement started to parody and discredit the usual conspirationist theories, using similar argumentative tactics. I don't know if some people actually take it seriously. Wouldn't surprise me.