Google Earth satellite imagery is also offered via Google Maps, at least for the most recent images. And Google Maps has a public interface which TransDEM makes use of - if you run the TransDEM
Map Tile Client. You may have to adjust the settings, see here:
viewtopic.php?f=7&t=451&p=2389#p2389.
With the Map Tile Client, each clipping, map or ortho-image, will be georeferenced automatically. You select the location, click Get Map and receive an image georeferenced and already converted to UTM. You also have the path option, for further automation, to acquire a series of maps/images along a given polyline.
There is a downside. Google limits access to the servers via this interface. After a few hundred clippings, they shut you out for 24 hours, based on your IP address. Then, the URL changes quite often, at least it did so in the past. And this map tile interface may be retired in the not so distant future.
This is pure speculation but there are a couple indicators which suggest this. There is, however, an official Web API, as a rudimentary REST service, which TransDEM could use instead. Unfortunately, that service is incompatible with the tile map de-facto standard. And it will require a key, which Google provides "free-of-charge", in exchange for collecting your data, of course, as they do with Google Earth.