Thanks.
When I read your reply it occured to me that my initial post might be construed as if we magically could sing those two songs without ever having rehearsed them!
I wish we were that good, but no; what I meant was, that we hadn't sung them that evening before quickly recording those vids. We just wanted to see if we still remembered the voices from earlier get-togethers.
We should have recorded 'Surfer Girl' though. That one we can harmonise in our sleep by now.