Fix index page for Internet Explorer

This page stinks anyway.
Work-around for lack of video texture support in Internet Explorer #68
Don't use magic number for WebGL error code (#68)
Remove unnecessary variable initialization
Added unit tests for video source

Known to fail in Safari 7, which reports canplaythrough before video data is actually ready
Merge pull request #70 from brianchirls/video-texture-workaround

Work-around for lack of video texture support in Internet Explorer #68