The first video is silly the earth takes 23 hours, 56 minutes, and 4.09 seconds. It then takes another 3 minutes and 55.51 seconds to point back at the sun. Humans chose 24 hours to be from noon to noon based on the sun, not based on the position of the stars. This is also, in part, why there is a leap day.

If there is no curve, why do the rigs have different heights? https://imgur.com/a/Aec5VnM

The laser light experiment is dumb because light spreads out like a cone. Yes, even lasers.

If there is no curve, why do the rigs have different heights?

https://imgur.com/a/Aec5VnM