One of the points of my post was the speed and force of blue has no impact. red has not moved in the direction of which blue was going. The cause of how red ends up in the air is his own speed. Blue could have been 10 times slower but red would have still ended up the same because of his own speed.
Yes blue knew if goes for the tackle there will be a collision. So did red. Its clear to me that blue did not 'hit' red hers. It was red who collided with blue.
I did a number of times before posting. In full speed and slow motion, freeze frame and so on. My post may make more sense of you watched it in the same way.