I reckon that sums it up although I might take it a stage further - the tune comes from the original MS which is then studied by Early Music Academics and Professionals who go on the make performance editions and recordings which people like Corvus Corax pick up on their travels and arrange it to suit. No harm in this of course - it's a time honoured tradition.

Authentic? Well, I'd sat they're as authentic as anyone playing 14th century music in the 21st century - it's the lightshows & Klingon showboating I'm not so sure about. Check that ealier clip of David Munrow giving it laldie back in 1976 on a Chinese Shawm (about £3 from Ray Man back then though these days you'd be paying more for the reeds!). And another clip of the venerable Oni Wytars giving Istampitta Isbella a rare old dressing down on a very modern looking nykelharpa (played by Marco Ambrosini).

http://www.youtube.com/watch?v=fICHPEAguJQ

Please let Authenticity be the reserve of Model Railway enthusiasts who would at least recognise a real train should ever they see one. Munrow, Oni Wytars, Corvus Corax - bless 'em all I say!