Your video contains just the first 3 lines of the hymn:
Pange, lingua, gloriósi
Córporis mystérium,
Sanguinísque pretiósi,...
Because they are the first lines of the hymn you can also hear them immediately at the beginning of the video I posted.
(The only differences are the wrong pronunciation of “Pange” in your video and the faster singing in my video, which is typical for Gregorian Chant sung by French.)