This Thingy is very simple, it lets you connect two 15-pin 1.0mm pitch cables end-to-end and extend the length. It does the funky pin rearranging and all for you, so just snap those two cables in. Carefully pry the two ears of the connectors, plug the cables with contacts pointing up, and then push the ears back in for a solid connection.
In theory, the CSI/DSI interface isn't meant for super long cables, and you're not supposed to extend them. But we laugh in the face of theory. We connected two 1 meter long extension cables using this Thingy and our Display and Camera worked! But, just so you know, it's really not guaranteed: CSI/DSI are meant for maybe 25cm max length.
For use with classic 15-pin 1.0mm pitch flex cables, does not fit the Pi Zero's skinny CSI connector. For that you'll need to use an adapter first!