If someone has info that this clip is anything but Kraft Music Hall, Feb 1969 aired on NBC, please add it. Otherwise I'm 99% sure that's exactly where this was taken from. In this case since it was a California themed episode of that variety show, it would make sense for them to do this song. Then they also did "I Can Hear Music" which would have been a contemporary song for them to feature, so it evened out. Why they would do California Girls on something like Dutch TV is more of a mystery, but consider maybe that's what the fans watching those shows would have expected them to do, or maybe that's what the show itself asked them to do? It's odd but it was a big hit so maybe there was still demand in Europe into 68-69 for them to do these hits from 65-66 on TV appearances.
It has been years since I watched the "20th Anniversary" TV special, but my recollection is that that special specifically mentions that the clip is from Kraft Music Hall. I don't think there's any doubt that it's from that show.
As for European TV appearance, I don't think the *reason* for them miming to old tracks is odd or unclear. A lot of those shows were only set up for "American Bandstand" style lip-sync deals, and so they were just using the original tracks because that's all they had. The oddness is mainly in hearing but not seeing Brian, and the vintage of the songs. Can anybody imagine the "White Album" or "Get Back" era Beatles miming to "Please Please Me?" The Beach Boys mimed to "Surfin' USA" on the Beat Club in '68 or '69.