You seem to be adverse to providing "text" examples. I don't want to watch 45 minutes of video to learn how it should be done, I want you to provide us with the "condensed" results of how you did it. Specifically, what works and what doesn't and when it doesn't work, detailed error messages (if any) or a "text" description of what appears to be wrong.
For example, if I had set things up like those two videos, I would access both printers from my internal browser with "http://octopi:5000" and "http://octopi:5001". I would verify that both printers can be accessed simultaneously from two tabs on my browser, and that both printers can be printing at the same time.
Then, I would go to my router and add two port forwards, 5000 to 5000 and 5001 to 5001. I would verify that every Tom, Dick, and Harry could access my printer from any internet cafe in the world. I would then "freak out" and make sure I had some sort of access control so only I could connect from an internet cafe and Tom, Dick and Harry were at least forced to guess a username and password before accessing my printers.
I, in fact, do have internet access to my printer but I did so by setting up OpenVPN on my router. This provides the same protection as your online bank provides for your money.
I can also tell you that yesterday my firewall denied access to over 2,000 attempts, 23% from Russia and 11% from China. With a public IP address comes responsibility!