Reverse scan (i.e. mirror image) monitors are often used by puppeteers. In the old days you'd use a CRT with modified scans (it wasn't a standard feature), these days it's easier just to delegate a resizer or DME in the mixer and send it out via a spare aux output from the vision mixer.
I wouldn't worry about worrying whether something has been posted before, because the chances are it probably has. If in doubt I'd argue if a video was uploaded this month it probably hasn't been posted here.