webrtc error with mime.lookup

use mime-type instead of mime. So, Install mime-types first:
    npm install mime-types
then make change in your code:
    var mime=require('mime-types');

I'm having the same issue with step 4. You can changing the node-static version from 0.7.7 to 0.7.10 in package.json and rerunning npm install

  "dependencies": {
    "node-static": "0.7.10",
    "socket.io": "1.2.0" }

if you have a folder "node modules" in your root directory,delete that and type npm cache clear and then type npm install.this should work fine