Firefox and IE give you that warning because they do not want to interact with indymedia’s certificate. Both browsers (most if not all) are part of the corporate world and only interact well with certificates created within the corporate world. Indymedia and friends keep out of the corporate world as much as possible. That is why they work with certificates that do not come from that world.

As a result, you need to click on the “red warning” and tell your browser that you trust this certificate. Ideally you would check the certificate as well, but just to make it work, it is fine to just click ok and save your certificate so that you can view the page. You need to say that you understand the risks and that you want to trust this certificate from now on.