AnalyticalGraphicsInc/cesium — pull request #1827 by curts (2014-06-11 20:50:03+00:00)
Title: Get video material and screen overlay working.

Code pulled from Greg Beatty's (@gbeatty) Powder Tracks example application (http://cesiumjs.org/demos/powdertracks.html).

Here is a screen shot of the HelloWorld sample with a small Screen Overlay containing a sample video:

![image](https://cloud.githubusercontent.com/assets/1950836/3250659/6c39009e-f1a8-11e3-98b6-2e0a349f3998.png)

### CZML Used
```javascript
{
"id":"demo.webm",
"availability":"2013-02-01T20:01:05Z/2013-02-01T20:03:03Z",
"screenOverlay":{
"width":256.0,
"height":128.0,
"show":true,
"position":{
"cartesian2":[
20.0,40.0
]
},
"material":{
"video":{
"loop":true,
"speed":1.0,
"startTime":{
"date":"2013-02-01T20:01:05Z"
},
"video":"demo.webm"
}
}
}
}
```