What are those weird sounds when using the external cam? Chain Saw ? Pistol Shots ? Some worker using a Power Tool ?
Most likely the ambient sounds placed by the route author/developer. They are in the editor (the speaker symbol).
I think he means the sounds of a few old, standard, widely used animations. One is an electric utility vehicle accelerating, then stopping. The other one is an excavator. As for the complaint, yes, these are not great. The electric one is particularly annoying after a while. Although the most annoying category to me is some road crossing sound, whether it's the old PDL, Bristol-Exeter or München-Garmisch.
Better than totally silent routes... and there are quite a few devoid of any ambient sounds. And the best being SAD's routes like Köblitz and Brennitz.
You can use OBS Studio or the Windows / Xbox game bar (Win+G). You can also simply localize where the sound comes from. I thought about the excavator loop because it has a collision element to it, be it dropping the stuff, or hitting something while picking it up. But there is the one dropping the pallets. There are some objects-with-sounds, most of these just go in a loop but the container loading is triggered by the event. Guess I should call them animated objects. In any event, fly around with Camera 8 while not paused, park your train in the distance and hunt for the source. Sounds files are packaged into GeoPcDx or similar, so can't play from Windows. Tends to be a strategy to make it difficult to steal these assets as well as modding.