Popcorn.js is an open source event framework for HTML5
<video> which provides an easy-to-use API for synchronizing interactive content.
It uses the native HTMLVideoElement properties, methods and events with normalizing them into a simplistic API.
The framework also provides a plugin system for community contributed interactions.
There are many functions provided for controlling the video like getting the duration, setting the playback rate or changing the volume.
And, there is Butter which is again an open source resource for authoring Popcorn.js.