playback is an video player build using electron (formerly known as atom-shell) and io.js. first you should install latest node.js or io.js (which installs npm). the easiest way to get started with development is to first clone this git repo and run
npm install
npm start video.mp4 # or some other .mp4 file you have laying around
this will open playback in development mode and it should start playing video.mp4.
the main entrypoint to the application is app.js which is executed by atom-shell.
this file spawns.js a webview that is run with index.html which includes index.js.
dont worry! just go to the issue page and find an issue marked "help wanted". these issues are normally well suited for people looking to help out in one way or the other