Presumably the data is stored in RAM (or potentially on a swap disk) by the browser. Most likely they are feeding the data into the Media Source Extensions [0]

Presumably the data is stored in RAM (or potentially on a swap disk) by the browser. Most likely they are feeding the data into the Media Source Extensions [0] APIs. I'm not sure why you can't seek to random positions. It seemed to work for me, after a few second delay (presumably to issue commands to start downloading different blocks). Those IP addresses are private network addresses. The machine you are connected to is probably behind a NAT and is connected to you through a different address. The UI is probably just showing the local address that that node reports. [0] https://w3c.github.io/media-source/ https://w3c.github.io/media-source/