There is no "pure" Irish - even within the 3 regions that we usually break the dialects down into there are significant variations. For instance, the new speaker speaks a version of Connacht Irish, but in some cases she uses Connacht terminology, and in other cases she reads the written text with a "learned" pronunciation, because that particular term might not have been familiar to her.
Basic Irish pronunciation is reasonably straightforward once you learn that, Irish, like French, and Italian and Spanish, doesn't use the same rules that English does for pronouncing things (that's what a Frenchman doesn't pronounce Paris the same way that English speakers do).
This video might help: https://www.youtube.com/watch?v=oIokUII7LX0
i'm typing what I think I'm hearing and Duolingo keeps telling me I'm typing in English, probably because "an" is also a word in English. The pronunciation sounds to me like "An cuislear". I'm sure it's perfert for some dialect, but it's nothing like the way I was thought caisleán in school!