I presumed such as was the clarity of the image that we were going to see the boat in the first video 'disappear' over the horizon. What happened?
What happened is as the first ship was mostly sunken he started to follow another ship which was coming towards him.
This is that second ship when he first starts to follow it and right near the end of the video:
If that isn't "evidence to go on" then I don't know what is. Where's the rest of it in that first image? Obviously you are free to do your own tests and satisfy yourself that the ships do completely disappear when they go far enough. I'd suggest the difference between those two frames needs some explanation on a FE.
Mostly sunken? Where did that come from? Are you watching a different video - obviously not one that you took or could be bothered to watch. Please go back and show me this 'mostly sunken' ship - I am dying to see it.