I'm a dev working on OpenVidu [1]. Just chiming in to say that OpenVidu is not an alternative to Zoom, but a toolbox you would use to create a Zoom alternative.
Think capturing video from the webcam, sending it out and distributing to other viewers, controlling publish/subscribe permissions, recording sessions, things like that are done by OpenVidu. You would then get those and put them together to build a Zoom-like product.
As part of the project, we do ship OpenVidu Call [2], which is a complete example of how to make a fully featured videocall app with OpenVidu.
One side project is on the way of becoming one of those ISO documents that costs 133 swiss franc. Some weekend I am going to get Pelican up and blog a bit about the three-sided cards and YOShInOn my RSS reader.