Just an anecdote but as a chemistry student I remembered lessons taught from an overhead far better than those from powerpoint. There was a stark contrast between the lower division organic chemistry series whose instructors used overheads, and the upper division organic chemistry mechanisms class whose teacher used slides. Those slides were mostly bullets and diagrams, sometimes with crude animations which were meant to indicate nucleophilic attack or whatever. Just watching the lecturer draw diagrams and arrows and listening to them talk was far more helpful, for me.
The lightbox seems much more overhead like in presentation. I dig it, and I hope today's college students learn well from it.
A physical overhead with the instructor's hand visible has been shown to work far better than presenting ready-made diagrams. It also works better than digital drawing, probably due to the natural inclusion of pointing gestures guiding students' attention [1].
There is also evidence (and good theoretical reasons to believe) that a transparent lightboard leads to unnecessary distraction/split attention. [2]
I have been using it for the past 15 years with great satisfaction.