After the Salve Regina at the end of Holy Mass...

At Saint-Eugène, M. Grodziski proceeded to the benedictio uvarum, the blessing of the new grapes, that is traditionally done on the feast of the Transfiguration. The grapes were brought to the altar accompanied by lit candles, sprinkled with holy water, incensed, and, having been blessed, were distributed to the people. From about 1:17:30 onward (the hymn O nata lux et lumine accompanies the sortie des clercs during the final few minutes of the recording). There is a way to clip a segment of a video for use but I haven't been bothered to investigate to see if that also works for use in this Blogger software.

The text of the benediction is as follows.

Béne + dic, Dómine, hos fructus novos víneæ, quos tu rore cœli, et abundántia pluviárum, et témporum serenitáte atque tranquillitáte, ad maturitátem perdúcere dignátus es, et dedísti eos ad usus nostros cum gratiárum actióne percípere in nómine Dómini nostri Jesu Christi: Qui tecum vivit et regnat in unitáte Spíritus Sancti Deus, per ómnia sǽcula sæculórum. Amen.

That is the text from the Rituale Romanum, at least from 1925 forward. But Dr Eleanor Parker, on her Patreon site, notes the version included in the Leofric Missal that is slightly i.e. insignificantly different but which uses a different conclusion. 

Benedic, Domine, et hoc fructus nouos uuæ, quos tu, Domine, per rorem cæli et inundantiam pluuiarum, et temporum serenitate atque tranquillitate, ad maturitatem perducere dignatus es, et dedisti ea ad usus nostros cum gratiarum actione percipere, in nomine domini nostri ihesu christi, per quem hec omnia, [Domine, semper bona creas].

'In the name of Our Lord Jesus Christ, through whom, Lord, Thou ever create those things that are good' while the Ritual's version adds the now-usual doxological closure instead. 

"For an Anglo-Saxon audience, the blessing of grapes, with its Eucharistic resonance, would make a very suitable pairing with the blessing of bread on Lammas Day, 1 August. Lammas is a harvest festival which only seems to have been celebrated in England, reflecting the agricultural seasons and priorities of a British climate, while the blessing of grapes came from another world altogether; but the idea is the same, and in early August, the beginning of the harvest season, the spirit of thanksgiving must have been universally appropriate."

Oh, I've just now (after I closed this post and hit 'publish', tsk) found M. Henri de Villiers's essay about the benedictio uvarum here.

Post Nonam. I'm rather dense. The benedictio from the Leofric Missal 'sounds familiar' perhaps because it was, formerly and at some point in its history, included at the end of and as part of the Canon Romanus, the great Eucharistic Anaphora of the Roman Church:

Per quem hæc omnia, Domine, semper bona creas, sanctificas, vivificas, benedicis, et præstas nobis.

The Leofrician benediction, if this is the case, is to be read, ... percipere, in nomine Domini Nostri Iesu Christi. Per quem haec omnia, Domine, semper bona creas, sanctificas, vivificas, benedicis, et praestas nobis. Per ipsum, et cum ipso, et in ipso... et cetera.

M. de Villiers points this out  (precipitating the revelation of my obtuseness):

'The benediction of the first fruits of the grape is fixed on August 6 in the Gregorian Sacramentary (6th-7th century). This blessing took place during the Mass of the day which was not yet that of the Transfiguration (which feast appeared late in the Roman Missal, only in 1456/1457) but is that of the feast of Pope Saint Sixtus II, the 24th pope who had been beheaded in 258. As with other very ancient blessings, the Benedictio uvæ found its place at the end of the Eucharistic Canon.' 

Unfortunately, I'm rather done with grapes for the day.