Bug 896907 - [Camera] No preview shown for successful video pick activity

Hi David,

In this patch we are using filmstrip methods to preview an video.
1. calling preview item with a delay (delay is used because the addVideo function takes time to create thumbnail, other stuff)
2. creating dynamic values for videoPoster and videoPlayer css values. This was done to maintain separate values for video pick activity
3. Bringing confirmation to the front by making z-index value to 110 (highest)
4. Hiding toggle flash and toggle camera button for image and video preview of pick activity.

Please review the patch.