Very interesting. I've implemented something similar. It evolved out of the co-browsing solution I developed for the company I work for.

The solution uses mqtt. Clients subscribe to a topic on the server, and the server publishes patches to update the view. Patches can be incremental (patch against the last frame), cumulative (patch agains the last keyframe) or a new keyframe. It allows for server side rendered views. Multiple clients can subscribe to the same view and keep in sync. See: https://github.com/mmzeeman/zotonic_mod_teleview