This is John Britton, not Jeff Lawson, but an example of the live coding. Epic demo: https://www.youtube.com/watch?v=-VuXIgp9S7o

Here's the time he built "Hawk or Not" with Tony Hawk: https://www.youtube.com/watch?v=fxHYyD3upNc&t=6120s

Here's a good recording of a very smooth Twilio demo at "Yahoo! Hack Europe: London" in 2013 by Michael Wawra:

https://www.youtube.com/watch?v=mPAe0rJApvk