An experiment with PHP and socketio to share your screen in a pretty low rate (because PHP)
NodeJS PHP running php_sockets extension enabled on php.ini
$ git clone https://github.com/ikarius6/Screen-Viewer
$ cd Screen-Viewer
$ npm install socket.io
On a term run the socketio server
$ node screen.js
Open screen.html on any browser (double clic it's ok)
On another term run the broadcaster
$ php screen.php
It could run on local network just by changing the IPs correctly