Video confidence

Added video confidence.

These are the basic metrics...

Preroll starts / video page views
Preroll ends / video page views
Video starts / video page views
Vide ends / video page views

![confident](https://cloud.githubusercontent.com/assets/76709/3738190/1990bff6-173e-11e4-8d2d-087cf19e0fe2.png)

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