@odranreb I tried to put your URL into an IFrame inside of a CodePen and it also fails, which leads me to believe the problem is the server at mooo.com and not the Web App.
My guess is that a recent browser update is not allowing you to display non-HTTPS content in an HTTPS context (The Web App has mandatory HTTPS).
@odranreb Opening a page in a tab is not the same thing as opening a page in an iFrame. Browsers follow a number of security policies for handling iframes which do not apply to tabs. I understand your reason for using a dynamic DNS, and it does not contribute to the problem.
The error message on Firefox is a bit easier to understand:
You can read about Chrome’s decision to block all mixed content (Oct 3 2019) here.
You can read about Firefox’s mixed content blocking (and why browsers do it) here.
This is a problem with your browser / web cam. Your best option would be to upgrade to HTTPS, purchase a camera that hosts HTTPS streams or find a way to proxy traffic over an HTTPS endpoint.