It depends what technology you are going to use.
In case of WebSocket you will need JS on client side and you will also need WS server implementation in python to connect to. Then again, going for pure WS will create plenty of issues (browser compatibility, etc.). I suggest you to start with socket.io: JS client + python server library (https://github.com/miguelgrinberg/python-socketio). This should make it easier for you to start.
The above also applies to WebRTC - you will probably want to find a library to handle all differences between browsers. Just keep in mind WebRTC alone is peer2peer, meaning there’s no server involved (of course your server application may be a peer itself).
But if your ultimate goal is to receive video from somewhere, process it on your server and serve via web page, you may save some time looking into web video streaming, HTML5 is quite capable of handling video streams nowadays. So HTML5 video streaming + RTP + RSTP could be your friends here (and keywords to conduct research).