I love devotion, not because I am religious, but because devotion reflects depth, unwavering strength of purpose, dedication, and purity of intention. These qualities are rare, and pull me in their direction.
The sound quality and images lead me to believe this was recorded in a cave during his pilgrimage to mount Kailash. It has always sounded to me as if there are two voices. If not, that then a one frame delay on the second channel creates that lovely echo/second voice.
To find and follow the verses chanted in this extra-ordinary video (audio really, video is secondary) scroll way down the page to where the video is posted, begin looking in the text after verse 25, before it restarts at 1, at 2nd occurrence of OM, written above the video frame. At 48 seconds in, the second OM.
To go deeper, forget all that and listen with eyes closed.