About ten years ago I recall re-linking a ZDF broadcasting station's 1989 documentary on Batmania ("Batman-Welle") on here that I had found on YouTube. Unfortunately I didn't save it before it got deleted. All I found was a clip with a musician talking about Batman from said broadcast:
https://www.youtube.com/watch?v=LYxchU7Qrw4 (https://www.youtube.com/watch?v=LYxchU7Qrw4)
Among other things it included Michael Keaton arriving at a German airport, disco owners talking about Bat-Mania, unique behind the scenes material, etc.
So I turn to you in hope that someone downloaded the video off YouTube before it was deleted.
On a side note, while searching for said video I found a french broadcast from 1989 giving an inside look into the development of the Batman Game by OCEAN:
Micromania Video Show 01 - 1989 - Reportage OCEAN Software
https://youtu.be/eJ4FB_Yb3Fg?t=1m38s