Write over live stream video

How can different users write words or sentences, at the same time, that appear on a live video streaming?

Are you suggesting a shared sketch or just a single sketch? The former would require some kind of server or perhaps just saving to a network drive, (not attempted before so I’m not the most knowledgeable).

Then you could use a network location to save and read saved files.

The text could be read from a single host sketch and displayed onto a screen.