Originally Posted by DaleDe
You are a bit ahead of the curve. ePub as currently released does not support mp4 or mp3. The current release is version 2 and version 3 is still just a talking version, not yet released or implemented. Version 3 does do what you want. This is also an HTML5 issue so browsers running HTML5 will have this feature but it is not yet released as a standard either although Apple is pushing it.
There is an online site that allows you to create multimedia epubs that can be read online using Chrome. Chrome supports video and audio. You can download the epub for use with mobile devices such as iPad that supports multimedia video/audio. Take a look at [pirate site], or for education groups, try [pirate site] that supports group sharing of epub ebooks.