The video quality is very high. However, just this: it is highly recommended listening with headphones (or at least with ear-phones or small loudspeakers),
otherwise the 1/2 of the richness of harmonies will not be really audible on a standard computer (and for example, at the beginning of the piece, the cello begins with a very light, almost imperceptible friction -and the same thing at the end-).
"The Cloud of unknowning" is the title of a short anonymous English book - during Century XIV-, with a "rather mystical" and particularly modern vision.
And very old too. Free of Time, as free as the air in fact.