Looks like they're randomly dropping the viewer until they get a hit (I've gone over "searching (600)"). I wonder if there's a faster way to do that with their API?
Completely random drop would fare really bad (street view is very rare compared to Earth's surface). What I would do is a sort of "computer vision". Map has well defined colors for features, so you just need to check pixels with proper shading. This should be quite easy as street view availability seems like a transparent overlay image, so you even wouldn't need to distinguish it from other map features. And even if…
For you interest and information, he has a defined set of bounding boxes in the world for each of the user pickable regions. He generates random lat lons until one lands in an enabled region's bounding box and then makes a request for street view data to google. If google returns a 200 he sets the street view display to the lat Lon and otherwise tries to find another lat Lon. If he ever gets a 500 from Google he quits.