Eeeeh, I see where you're coming from (and I most certainly agree that the Irish people were treated horrifically by the British and, later, America as well) but I think you're missing the point about the PoC only spaces. That video you're referring to I believe was of Bernie Sanders having the mic taken away from his at a political event - this wasn't done by the broader BLM movement but rather two extremists whose views are fairly atypical.

He wasn't kicked out for being white, though - he had the mic taken from him because these two activists wanted to shed more light on racial issues in the US, particularly concerning the African American community, because they felt white progressives sort of ignored them. And they do, honestly - I think Bernie Sanders is an exception to this, though.

But any POC spaces (I mean, I don't even know to what extent they actually exist, to be honest with ya) exist just to give people a bit of a safe space where they can discuss issues that frankly a lot of people can't really empathize with just because they haven't experienced racism in the same way. It's all very well and good to say "We should see each other as people, not colors guys!" but that doesn't really work when the system is so ultimately rigged to see people as inherently different. You gotta start somewhere to get that ultimate egalitarian goal - and even then, it's a goal that will probably never, ever be achieved because people are a bit shit at treating others as equals, as the occupation of Ireland very clearly showed. Shit, if you had a English guy in 17th century Ireland walking into a pub and declaring HEY GUYS LET'S JUST GET OVER THIS DISCRIMINATORY DIVIDE AND BE COOL, he'd get a pretty rude answer. I mean, fuck, if you had an English person today going into Ireland or Northern Ireland and just saying "Oh hey that's all water under the bridge, you don't have to be so bitter about it all, couldn't have been that bad, amirite?" he'd get a rude response, and deservedly so.

White people aren't inherently racist. I don't agree with anyone who says otherwise. But it's important to note that Irish people weren't seen as human - heck I don't even think they were seen as white. They were seen, much like Asians and Africans and etc were, as a different race. So you could argue that because they weren't seen as white they didn't get the benefits of being white. The same goes for the Polish and Eastern Europeans and people from the Caucasus.