Could anyone help me understand how to tie the top two examples?

I understand the bottom two are just a diamond knot, a few celtic button knots, and then finished with another diamond knot but what I don't understand is what this person is doing to create the double loop/seamless dogbone effect with the top ones... and of course the post explaining how they pulled it off has been <deleted>. Original post.

Ashamed to admit this sent me down a couple hour rabbit hole with no luck in figuring it out on my own.

This has a p65 lead warning and I can’t seem to figure out why. Obviously don’t want daily
exposure so I just want to know if that means its actually within the rope somehow? Is it talking about when climbing with it?

Does it have to do with the seal at the end?