I’ve experienced the same issue, it only works when the mp4 is online.
Had it work online by following these instructions: Can't play HTML5 video content on Android
Also, it appears there are known issue’s with playing mp4 locally. However, i’m a complete newbie to angularjs, cordova , just trying to help any way i can:
ref: http://www.telerik.com/forums/embedded-local-video-file-not-playing-on-android