I agree. I usually cringe at the way the Anthem is arranged (especially for SATB), but whoever arranged this for five-part girls did an exceptional job.
Those who have never been a member of a choir might not have noticed this, but the girls started off right on pitch, without any use of a pitchpipe (as far as I could see) — something not easy to do. They also stayed right in key and did not rush the tempo. An excellent, excellent performance!
It’s likely that at least one of them has perfect pitch and hummed the starting note. My brother sang with a a cappella group in which no one had perfect pitch so one of the tenors carried a tuning fork and subtly got the A, and hummed it. That guy was good, even though I knew what they were doing, it took like, three songs for me to figure out who had the fork.
A beautiful arrangement and execution.