I am affraid this is quite different to the "traditional latin chant"! 1. This is not a chant (as in the traditional sense); 2. It is not modal. 3. It is not found in the Gradule Romanum.
The real chant entitled 'Lauda Sion' is to be found in the Graduale Romanum immediately after the Alleluia in the Proper for Corpus Christi. It is in mode VII.
Therefore the Description for this videoought not to be "Traditional latin chant'.
Nevertheless, it is lovely, thanks.