Each demo includes some aspect of interactivity. For example, the typography demo lets you insert and manipulate your own text, while the video lets you scale the movie, apply a mask, and change the perspective. In addition, each demo explains how it was made and offers sample code from the Safari Dev Center.
Note that Safari -- mobile or desktop -- is required.
"Standards aren't add-ons to the Web. They are the Web."
[Via Daring Fireball]