as it turns out, it's not just gibberish. It's legit Scottish slang. The top rated youtube comment explain much of it, and a reply corrects what that person got wrong.

I only knew "tatty" as "potato" because of an old episode of Anthony Bourdain's "A Cook's Tour", where he and his Scottish guide had neeps (turnips) and tatties along with some haggis.

cultural contrast between the Japanese, who have relatively few swears, and the Scottish, who have nearly nothing but.

today I asked a coworker to explain how you know if something is shite or pish.

Let me rephrase. The words are indeed authentic Scots slang with the proper dialectic inflections. My point above regarded the stringing togehter of words into the whole of the insult, which is word salad. Following from boner's point, this is pish rather than shite.

Shite is anything that is genuinely untrue. Pish is a mixture of truth and lies.