Watch:

The gun does not recoil until ten bullet is well out of the barrel.

So, yet another lie from the rabbibot and his sockpuppet Chum.

The initial recoil is captured by the slide of the gun. That uses the recoil to eject the empty cartridge and load the next round.

But it can only move so far, and the springs start transferring force to the rest of the pistol and by extension the hand.

If you watch the video, you notice the main body of the pistol starts moving backwards before the gasses finish exiting the barrel, showing quite conclusively that gasses reentering the barrel is not required to produce recoil.

As for gravity, rab said it doesn't always accelerate things down. Regarding satellites, that depends on what you mean by "down".

As the acceleration due to gravity keeps them in an orbit, it can be said that it doesn't accelerate them down.

This is a combination of their inertia and the curvature of Earth (more technically the curvature of their orbital path). Their inertia would take them off to the side, with the curvature of Earth resulting in the distance to Earth increasing and thus apparently making them go up (aka the apparent centrifugal force). Gravity combats this and keeps the roughly the same distance from Earth.

If it was in a sub-orbital trajectory, gravity would win and pull them down to Earth.

If they were in an escape trajectory, the curvature of Earth wins and they go flying off, with the acceleration due to gravity being too weak to bring them back down to Earth.

For an elliptical orbit, it oscillates between the 2. At one stage their forward (equivalent to the horizontal component for a circular orbit) velocity is greater than that for a circular orbit and the curvature of Earth wins and they get higher, slowing down in the process. At other stages (i.e. after they slow down enough) their forward component is too small, and gravity wins pulling them down accelerating them in the process until their forwards speed is too great.

The reason gravity can affect their forwards velocity is because their path is no tangential to gravity at all times.

And all of this is irrelevant to the OP.

Can you explain why the towers appear to follow the curvature of a round Earth if Earth was flat?

Lens distortion as well as the towers curving left or right have already been ruled out as possible contributors.