Should it not be office DE tourisme?

JS, 

It is not just the transcript, the speaker clearly says ‘ l’office du tourisme …’.     

The general term is ‘ office de tourisme ‘. 

However, when referring to a specific office, particularly  such as in the case here  ‘ office of (the) tourism of Ajaccio ‘ it is more common to use ‘ office du (de le ) tourisme d’Ajaccio ‘. 

When offices fill multiple general functions eg ‘ Office de tourisme, (des loisirs) et des congrès ’ or similar, it usually remains ‘ de tourisme ‘.

https://www.entreprises.gouv.fr/espace-entreprises/s-informer-sur-la-reglementation/les-offices-de-tourisme

https://www.tripadvisor.com.au/Attraction_Review-g187211-d8737191-Reviews-Office_du_Tourisme_Arles_Camargue-Arles_Bouches_du_Rhone_Provence_Alpes_Cote_d_Az.html 

https://australie-a-la-carte.com/office-du-tourisme-australie 

https://www.office-tourisme-usa.com/preparez-votre-voyage/formalites-dentree/

https://www.marseille-tourisme.com/ 

https://en.canaldes2mersavelo.com/useful-information/tourist-offices/office-de-tourisme-et-des-congres-de-bordeaux-metropole

It can be either (https://fr.wikipedia.org/wiki/Office_de_tourisme) but I think it's more commonly expressed with a de