I'm trying to understand the various chroma based transparency effect filters available and how one would choose between them. I believe I get why one would choose between blue and green. My impression is that one would choose "Chromo Key" if the background were some other color. Please correct me if there is more to this than that. "Non Red" seems self explanatory but can't guess what this is used for, i.e. why "red"?. Can anyone tell me? Then there is "video merge", is there any reason to choose this or not over the preceding chroma keys on a Windows pc?
You can use Chroma Key for blue as well as green and a variety of other. The Videomerge is supposed to be an "automated Chroma Key". I prefer the Chroma Key.
Have you looked at the Difference Key which can be a good subtitute for the Chroma Key, Blue Screen Key, and Green Screen Key which are not available in Premiere Elements Mac. Premiere Elements Windows users can use it also.
Have you looked at the Adobe document (Effects Reference) that details these Keying Effects?