The legal problem was exactly the same with TileProxy, or any other piece of software allowing you to download the pictures from any of the main servers (Google map, Bong etc...), wasn't it ?
Concerning the sceneries, it is possible to generate your own autogen based on OSM data using some useful freeware tooks like ScenProc.
Then you just need to move that autogen (AGN files) into the corresponding area folder, and you'll get autogen on your downloaded photoscenery.
For the record, nowadays autogen on large photoreal tiles looks great. It used to be quite ugly, indeed, but that was the past.
That being said, I tried that "World Terrain" with the free trial period (15 days) this morning for an area around the north of Japan.
It did work quite well, although my network connection was too slow.
I also generated some autogen for that area but unfortunately, I choose a bad source which was pretty empty for that area (openstreetmap.org). A few buildings appeared nevertheless, so it was at least of proof of concept.