I, too, have the same problem in Chrome on a Mac (OS X 10.9.4). And for me, too, this played fine in Firefox (thank you Pies for the idea!!).
I have NO idea why this is, but figured I'd let you know.
I DID like the video, though! This provided a very clear explanation (and showing) of the change to the default 'git push' configuration. Thank you for taking the time to record this for us.