I signed up anyway. Since giving them my email, I haven't gotten the stream to work for more than a minute before it deciding it's unavailable...and I hear him too before it decides to end it, so I'm confused. I was warned by a pane that it's in beta, I supposed. After a few tries, it seems to work now.

Ie. warning, choppy user experience.

EDIT: It was actually pretty interesting. He took a random piece of code someone shared and ran it, not after eye checking it first, of course. It ran something meant for cellular automata(?) which actually printed out the sender's name in the grid. Besides the fun, it was interesting watching Wolfram himself code live--very cordial and friendly. I'd definitely want to check out the next one.