The new HTML5 development features in NetBeans 7.3 (codenamed Project Easel) were first publicly introduced at the JavaOne San Francisco conference in October 2012. Project Easel was featured in several conference sessions and BOFs, as well as in the main Technical Keynote.
If you did not attend the conference, or missed the Easel sessions, or planned to attend them but could not get into the room (yes, some of the sessions were completely packed!), the good news is that you can watch the recorded sessions online. Presentation slides are available for download as well. This will give you a more in-depth overview of Easel than the screencasts at netbeans.org. So without further ado, here are the links to the recorded JavaOne 2012 sessions related to new HTML5 development features in NetBeans 7.3, by speakers John Brock, David Konecny and John Ceccarelli:
JavaOne Technical Keynote (Easel demo starts at 1:23:30)
Project EASEL: Developing and Managing HTML5 in a Java World
How-to: HTML5 Front-End Applications with a Java EE Back End