ok what hes doing with that retarded helicopter example is the air is moving 1k mph and the earth is moving 1k mph so for a stand still lift off theres no air really pushing us but with that tiny helicopter he is going about 1005 mph vs 1k mph wind and that 5 mph wind is what u feel and that is what's making it move diagonally... and to explain his second part about the air going along with us the air is actually getting shifted with the spinning earth...

imagine when u were a kid in a bath tub and the waters still but then u want to make a whirlpool so you start spinning ur hand(the earth) and it makes a whirlpool :O in the middle its as fast as ur hand was going but aroudn the edges its slower ( thats why to us it is very windy the higher u go)

now for the satalite going straight up and diagonally your going 1k mph around a circle(your going to have to imagine this) and its a huge friggin circle now lets say the circle is 1k miles radius the orbit its going is only like 1010 miles from the core so thats only +1% of the circle! now imagine that dot is going 1k mph around the smaller circle in 1 hour it will go all 360 degrees which is 3.14 million miles :O! but if it went that speed on the 1010 it would only go roughly 355 degrees (not a full circle) and would have still gone 3.14 million miles the reason you get that diagonal isnt because it slows down but because its going into a bigger circle where it needs to go faster to make the same circle around it sorry im bad at explaining things hope this helped