Live Streaming Between Appian Users

YOu can insert videos in Appian, but I think that there is no way to implement Live Streaming actually

You can't do it within Appian but there is a possibility of creating a deep link to a video conferencing app.

Here is an example for MS Teams: learn.microsoft.com/.../deep-link-workflow

Appian itself doesn't have built-in video conferencing.
I didn't try  but  you can give one chance :- Call integration to embed the chosen service's web interface.