Where do they find clips like these?

I've searched everywhere yet I cannot find clips similar to these:

You can watch this video over and over again so that tiktok's AI can recognize and your platform appear more similar videos. Of course, I don't really understand what you mean by similar videos. But I often come across videos on the same topic if I watch one video long enough or more than several times. As for how to edit or create a similar video, you probably not see a similar one, but I don't believe it is.

They followed people who posted such topics and then reposted.
Or maybe they curate videos and photos and then stage them

Ticktok would recommend that if you often watch things related.

Video stock agencies ?
Pond5, adobe, istockphoto, shutterstock etc...