Right so don’t really know if this is bait… but that’s one kind of accent (and the tickest pronunciation at that) in ulster, specifically greater Belfast/co. Antrim and very few people speak that thick. For the most part they should be quite understandable from the perspective of anyone who consumes any English language media outside of only American or only London (RP) English. The number of times I have had people have trouble with my accent in Europe and then I ask them what they watched when learning English and the answer is American TV is astounding.
This is me getting on my wee podium now but I have a huge problem with the Americans and Brits for this, they marginalise the fuck out if our dialect, make fun of it for being unitelligible (after making no effort to understand it), and often deny it any legitimacy.
In reality Irish English is spoken by 5-7million people, as large as some dialects of European languages (eg. Austrian/swiss German, Belgian/Swiss French, etc) and if you learn French or German you still get some exposure to those dialects and if you out your mind to it understand it.
It’s definitely creating more of a case to defederate from it if it ever tries to federate