You can also do this manually (and on older browsers) by creating a FileReader and only loading new chunks after old ones have been transferred. With async APIs like WebSockets and WebRTC this typically requires implementing your own backpressure to avoid blowing up browser memory. See for example how omnistreams does it[0].

[0]: https://github.com/omnistreams/omnistreams-filereader-js/blo...