This was discussed in https://news.ycombinator.com/item?id=19738313 in April
In networks with captive portals, the DHCP provided DNS will have a record for a URL where the user has to enter credentials or at the very least agree to the terms and conditions. Very often though, that URL only resolves locally, so in my setup the captive portal setup doesn't work seamlessly.
Recordings tends to show up YouTube.. later. This talk was also live-streamed earlier today.
Video from previous years: https://www.youtube.com/channel/UCuQhwHMJ0yK2zlfyRr1XZ_Q/vid...
I'm always surprised this conference isn't larger, it always has a wide breadth of low-level technical C/systems talks, with a mix of Unix/networking sysadmin content.