Buffalo, the video you posted does not show ships going over the horizon. It only shows how magnification helps see stationary objects more clearly.
To do the experiment correctly, the ship needs to be sailing away from the observer. Not laterally like some of the boats in the video, but directly away. Then, even with the most powerful telescope, the ship will slip over the horizon. Here is a video demonstrating this experiment:
https://www.youtube.com/watch?v=7nUFLLUahSINotice that as the sailboat goes over the horizon, the hull of the boat disappears but the sail is still visible. This isn't a problem with the telescope not being powerful enough. Rather, the earth is round.