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.
Hitbox.tv
Hitbox had about 6 million monthly active users in its later months. It has been announced officially use the HTML5 video player instead of using the Flash Video player.