Adobe Flash Player
Steve Jobs also claimed that a large percentage of the video on the Internet is supported on iOS, since many popular video sharing websites such as YouTube have published video content in an HTML5 compatible format, enabling videos to playback in mobile web browsers even without Flash Player.
Comparison of HTML5 and Flash
Tools for HTML5 are just starting to come to market; in the meantime, Adobe has released a first version of a Flash-to-HTML5 conversion tool for existing content and are working on creating new tooling for HTML5 as well, like Adobe Edge.