solve #1392: Make an estimate of the video size and indicate it's an estimate

When we have no record of the video size (aka it's 0MB), output our estimate of the video size, based on the average size of the videos. The average is set at 14 MB.

![frestimate](https://f.cloud.github.com/assets/191955/2073096/ca71bcc2-8d4f-11e3-84d7-ca6fcd90acf3.png)