Can I create a mask or Can I create Chroma Keying and Masking in Photostory ? I want to add a video clip of an interview and on the background to show/run different photos
Strangely, no. I thought that it was in an older version that I had, but since I no longer have it, I can't say.
You can do overlays and then apply a mask using the cookie cutter, which in my English version is called "Stanzformen." This should help you as you can define the shape and size of the mask. You don't actually see the mask, just the hole.
The best is to get the full program, Movie Edit Pro Plus or Premium.