OK, so I have to admit that I have never heard of or seen a document camera. That said, the Ladibug is incredibly interesting, and really a modern day overhead projector. It works in very much the same way as an overhead projector, but through a digital projector.
Essentially, you plug the Ladibug into a computer, and transmit the video captured from the Ladibug through a digital projector. Here is how the process is described on a Ladibug Amazon Product Page:
It is easy to set up, and connects directly to your computer through a USB cable. It is a plug and play document camera that can be connected to your computer for installation and power. The USB can be connected to interactive whiteboards to provide seamless integration. The USB provides speed up to 480 Mbps, ensuring fast transfer of data. The Lumens DC-120 [Ladibug] displays high resolution crystal clear images, has a built in microphone and built in lamp.
We had a chance to stop by the Ladibug booth at the 2014 FETC. We learned a little bit more about the product and saw it in action:
Check out all of our coverage of the 2014 Florida Educational Technology Conference (FETC)