This blend contains 1 worlds.
The others are in the attached file.
To make your own HDR:
This gives me some ideas. Would like to suggest the following:
I had to setup nodes to mix (or add)you other HDRI's provided in the folder. It's an idea to give an example, some users might not get the idea. Probably they expect to see the foto-studio in the blend-file as shown in the video.
You could provide some more info about how to use your blend-files and hdri's.
But this inspires me to make some HDRI's myself, make a nice node-setup in the World-node-editor so I can mix and rotate the HDRI's.