They use a site called The Code Player, which lets you see code being written in real time. You can use the controls at the bottom to increase the speed of the code (up to 20x) if you'd like.
When you open up a walkthrough, they may ask you to sign up, but you can just click play to get around that. There aren't audio overlays to these demos so, if you have questions, write them down and we'll discuss them with the group.
Check out this accordion menu demo from The Code Player. Most of the runtime is devoted to setting up the HTML and CSS, but it's a good look at the code in progress.