After much back and forth, I finally found the group chat solution I was looking for. 

The new chat I’ve included here is called “Rocket.Chat”

Rocket.Chat is an open source chat solution and offers a so-called “self-managed” installation. 
What does that mean? 

This chat runs completely on a chat server installed by myself within my own 4 walls. This means that everything that happens in the chat, be it the user data, the chats or the pictures and videos, are on the chat server and the hard drive at my home and not somewhere abroad (Russia or where else…). Uncontrolled access by third parties to the data is thus not possible.

There are several ways to use the chat. On the one hand, you can use the chat via the browser, whether embedded here on the livestream page or in a separate browser window. 
In addition, there are also programs for Rocket.Chat for the PC (Windows, macOS, Linux) or smartphone apps for Android and iOS on the iPhone. Thus, you can participate in the chat at any time without being on the website or without a web browser. It is also possible to upload pictures and videos directly to the chat via the smartphone app.

The links to the programs and apps and the necessary address to this chat are at the end of these explanations.

Data in the public chat rooms (messages, pictures, videos, etc.) older than 30 days will be deleted automatically. 
I ask you to consider that all pictures, videos and files uploaded in public chat channels can also be downloaded by anyone. Therefore, only upload files in chat if the circumstance is consciously accepted!

The chat can be entered as a guest without login or as a registered user with login.
However, as long as you are not logged in to the chat, you only have read rights. Active participation in the chat is only possible if you are logged in. 

A valid e-mail address is mandatory for registration. This is used to verify the account, but also to get a link to generate a new password in case of password loss. Your e-mail address remains secret and is visible in the entire chat for no one except the administrator.

What does the chat offer and how can you register? 
To explain it to you, I have prepared a small video explaining the registration and the main functions of the chat (in German only).

Below the video you will find more links with instructions for the chat. These are partly tutorials from colleges and universities that also use Rocket.Chat. It may be that some functions are explained in the tutorials that are not available here. But to explain the basic functions these tutorials are very good.

And just for now enjoy watching my explainer video 🙂 !