He is also merging images together, so he'd need to run the raw (unflipped) feed through a video processing program, and then back out (flipped) to his video switcher, and then capture that stream back. The switcher is how he adds video or powerpoint slides to the talk. It's really the video switcher that makes this whole thing a minimal post-production affair. So instead of adding another computer to the mix, he solves the problem with a $25 mirror that isn't very difficult to troubleshoot.
This could all be done in software like Max/MSP very easily, no hardware necessary except for capture cards, assuming the video cameras don't already stream over USB.
There's no such thing as live streaming without processing. The amount of additional processing needed to flip an image is so tiny as to be unworthy of consideration.
No, but it's likely more work, when you consider the hassle of setting it up and aligning it physically, vs simply using a camera that has a mirror function built in.
He could have learned mirrored writing. Would have allowed using the board in in-person lectures. Not that simple, but definitely possible: after 2 weeks of 2-hour almost-daily practice I've acquired quite decent skills at that.
I was sitting face to face at a table with a contact at my bank and all the time she was writing the numbers and diagrams facing me. I said that i was very impressed with her writing so he told me that writing backwards was actually part of their standard training at that bank, because they all have to write things on paper while facing customers like this so often :)
We did this for a school project. Found a large window on campus, wrote on it, then flipped it in a video editor. I guess if he is trying to go with zero post processing a mirror would work.
... couldn't he simply flip the output?