You're not going to find a lot of patience with people here on this matter, but I like to try to be constructive in all situations so I'll offer some advice and if you don't get banned it will be very helpful for you in the future. Have you ever noticed foreigners having trouble understanding an Irish person speaking with their accent and vernacular, especially when excited? That isn't exactly the speaker's problem, is it? They are who they are, they are what they are, they are from where they are from. If everyone was to conform to a "standard" of the most powerful nearby culture then Ireland would have stopped being Irish a long time ago.
I get that multicultural interactions are probably much less of a thing over there, but try to have some self-awareness. If you can understand how a person might find a person "speaking very Irish" hard to understand or annoying, yet how that is their own problem, then think how the same is true of you with peoples you are unfamiliar with. If I go to Singapore I'm going to expect their own way of using English which is different. If I go to rural southern states here in the US I'm going to expect them to speak differently.
Yeah, there are "standards" that are used for the news and whatnot, but those are essentially ethnocentric and classist, perhaps arguably a pragmatic standard for sake of their own medium. One may expect business to operate with its own culture and conformity but just a casual youtube is going to be personal and should be received as such. Tens of millions of people are very comfortable with the way he's speaking. A subculture doesn't need to be its own island or country to be legitimate (that's not a knock on Ireland, my own heritage is Irish, I'm just pointing out that people are usually go to islands with an open attitude expecting a unique culture and speech).
And if you do actually consider a heavy Irish way of speaking as "improper" and something to be "corrected in this day and age" then that is something here in the US we would call internalized racism.