Release Date of a TV episode Unknown ! What to do ?

Hi. 

There is one missing episode of the series "Wünsch dir was" (1969)

https://www.imdb.com/title/tt0472581/?ref_=ra_gb_ln?ref_=ra_dc_ln

There was a pilot episode recorded on 07.09.1969 which was not released on TV. 

But it exists and is uploaded on YouTube including all credits. 

https://www.youtube.com/watch?v=73BkNEJssIw

So it was released but I can't find out where and when.

What can be done?

Jochen