I don't know of any shortcut atm... there should be one, I see what you're saying, as sketchup has one so why wouldn't a 1500 euro program such as Lumion?
But in this case, after that last snapshot at the top of the tower I just flew way into the sky, spun the camera around and took another snapshot when I thought it was pretty well centered in the frame (I was actually a little off if you see the fade at the end into the "lethos" symbol), but it seems I should have used my tape measure on the screen first, lol.
I know this reply may have still not been very helpful, but I do implore you to spend time simply flying around your models. It was a pure joy for me zooming around that (empty) city for the first time at that speed as if I was an eagle on loads of caffeine . Just a wonderfully ambient environment, it was a good half hour before I started finding all the snapshots I wanted in the video....