Short as it is, this variation is not at all easy to play. The video shows how every single finger remains elastically attached to the keys, to allow for optimal velocity, accuracy and refinement, in particular also for the right hand's finger substitutions.
A beautiful four part setting with the melody in the bass (but without 16'). The two middle voices should flow like water and take the soprano and the bass along. Contrapuntal listening is essential here, hearing the flow of each voice separately and then trying to play it as you hear it inwardly. In the final chord, I played the high e on the great manual in stead of the positive (as indicated in the score), because the cromorne is too loud there.
In general, playing a choral is not so easy as it seems and often the result is too heavy, too 'vertical'. It asks for a 'horizontal', fluent way of playing, moving forward as in singing.
In this huge climax, one of the best in its genre, it is important to keep the fingers attached to the keys in an elastic way and not make the movements bigger than necessary.
Similar to Franck, Duruflé intensifies the movement of a choral setting with triplets in the middle and lower voices. These have to be played very steadily and fluently, else the effect will only be counterproductive. In this respect, particularly bars 67 until 72 ask for a lot of care.
In bar 31 it is important to have exactly the right change of tempo that serves to vitalize the adagio, otherwise the huge crescendo and dramatic climax at the end will not be well prepared. Play the double pedal in bars 41-45 completely legato for a good, powerful drive.
In bar 1, the indication dolcissimo makes clear that the toucher should be of the utmost delicacy and fluency. From bar 10, the swell box is opened stepwise, interfering with playing the pedals. In bar 19, con calore asks for a warm-hearted, generous unfolding of the five part setting.