Orff died in 1982. Copyright runs to 70 years after the composer's death. Try again in 34 years' time.

Pickett's, Sedayne's and Ambrosini's tunes are all related, all based on mediaeval sources, and none is a variant of Orff's tune, which shows no sign of having been derived from anything before the 20th century.

I think I saw Bill's video before it went, and Schott has him bang to rights. That's just the way it is.