It's a near virtuosic song, but Frida's pitch is perfect, and her expressive choices are beautiful. She's already a consummate professional, handling awkward questions at the beginning straightforwardly, firmly but lightly.
The segment reminds us of just how talented and, in Frida's case, feted the Abba boys and girls were as individuals. It's easy to imagine Frida fans from the '60s (and her teachers perhaps) originally tut-tutting that with Abba she was squandering her talent on pop music for kids, and that she was 'slumming it' by signing up with Benny and Bjorn in the 1970s.
Bonus Awesomeness: Frida sings a reworked Swedish version of 'Alice Blue Gown' in 1970. That vid. vaguely reminds one of Cremaster 1. And wouldn't Frida have made a great Queen of Chain for Cremaster 5 had Ursula Andress not done it?!