Understanding blob url video streaming

Many video stream websites, youtube for example, seem to have a blob url as their video source. Searching, I couldn’t figure out how this works. For example…

WebRTC Client side can not display remote stream on video element

I am trying to test a WebRTC application for video calling whose signalling server is written in Spring Boot. This is the client code that I am running. However in case of an offer, the local stream …