Some of the mystery may now finally be dispelled, at least for me, as in researching this item I found this comment on another blog that featured the same ad...
Andy Vaughn on August 23rd, 2007
I had the Batman Photo kit in the younger days. It consisted of 6 negatives with scenes from various Batman stories of the day (I remember a couple of them were Batman fighting the Bouncer). Several pieces of photo paper, and a hard plastic sheath were also included. You would take the photo paper, and place a negative over it, then place both in the plastic sheath which you would then hold up to a light source for 5 minutes. After that, a picture would appear from the negative onto the paper. It was really neat, and I remember playing with it for hours. However it was lost somewhere in time. Sure which I would have kept up with it!
And there you have it.