Unlike a previous "bardcore" video, that one shows no English accent and some effort to resemble the old French grammar. It is however still far too modern compared to the French that was, we believe, spoken in the 8th century. The oldest French text, the Oaths of Strasbourg (842), is closer to Latin and mostly unintelligible to French speakers:
Pro Deo amur et pro christian poblo et nostro commun salvament, d'ist di en avant, in quant Deus savir et podir me dunat, si salvarai eo, cist meon fradre Karlo, et in aiudha, et in cadhuna cosa, si cum om per dreit son fradra salvar dift, in o quid il mi altresi fazet, et ab Ludher nul plaid nunquam prindrai, qui meon vol cist meon fradre Karle in damno sit.
The pronunciation sounds a little bit too modern too. For example the diphtongs ui (sui, fui) is pronounced like it would be in current French (See Eau qui dort's comment).
Here is a transcription attempt of the dialogue:
Li Dus Rollo é/est a? non : Le Duc Rollo, voilà/est ? nom
Par moult sui liets de vos connoistre : je suis de très en liesse de vous connaître
Por bien, si pourrez, mes lèvres guardez : Pour bien, oui vous pourrez, (re)gardez mes lèvres
Païens sauvages fui, mais ores sui riches ver? de grant estre : J'étais un païen sauvage, mais aujourd'hui je suis riche ? de grand être (état?)