[mythtv] mythweb preview video thumbnail

[Chris Petersen]

I think I asked about this ages ago, but figured it wouldn't hurt to try 
again.

To support smaller themes, or maybe to provide a more detailed recording 
screen with a large thumbnail, I'd like to know if it's possible to 
request a specific size of thumbnail from the backend.

Also, if there is a way to get a "last edited" timestamp, I could use 
this to update thumbnails from with-commercial recordings after the 
recording has had the commercials stripped.

-Chris