If you don't know who Peter Brimelow is you can read his bio here but he happens to be the founder of VDARE.com.
In the interview he mentions some things that help explain the psychology (psychosis?) of the pro mass-immigration movement.
The obvious one is the assault on the living standards and culture of the working classes. Now, I should point out that he doesn't mention the cultural angle but it's one that I'll raise here because the assault on the working class is an attack from two fronts: the left and the right.
On the right we have the owners of capital. Immigration is, and always has been, an attack on the incomes of the working class. The most obvious historical example of this is the importation of cheap Asian labour, primarily Chinese labour, into North America in the construction of the national rail roads. This ever increasing supply of cheap and willing labour creates a downward pressure on wages resulting in the flow of capital upwards and concentrating it into fewer hands. And today it's the middle classes that are feeling its effects as their numbers are eroding under the weight of record household debt, stagnant incomes, an uncertain economic future, and a growing income gap between the rich and poor that is more pronounced than it was during the Great Depression. Immigration isn't solely to blame for this but it sure as hell isn't helping.
From the left the working class is being attacked on the cultural front. Working class culture is inherently conservative and thus are hated by the "progressives" for it because they stand as an obstacle to their agenda of refashioning Canada in their image. Immigration, primarily non-white immigration from the developing world, effectively neutralizes working class Canadian culture through the sustenance, promotion, and expansion of the multicultural program. By saying Canada is a multicultural country is to dismiss the existence of a dominant "mainstream" culture. And by dominant I mean the majority. And the will of the majority is what we call democracy. And if that majority, or a large portion of it, happens to be working class and conservative then things don't bode well for those with a "progressive" agenda. So you say Canada is a multicultural country; which is to say that there is no dominant mainstream culture; which is a clever way the "progressive" left get around that nasty thing we call popular will (i.e. democracy) and thus gives them license to change the country to how they see fit.
It's a divide and conquer strategy since immigrants typically flood into working class neighbourhoods because housing is more affordable. As a result the voting power of the conservative working class in those neighbourhoods is pacified and the electoral riding shifts left. Or at least it's supposed to because the last election proved that it's not a guaranteed outcome and the left may have in fact miscalculated and taken the immigrant/ethnic vote for granted.
In any event what I find sinister is how the "progressive" left infiltrated and co-opted the labour movement to advance their agenda and take it on a course that not only makes the labour movement unrecognisable to the working class but attacks them while at the same time claiming to be their champions. Things like multiculturalism, same sex marriage, and issues affecting the Middle East, among others, have little if anything to do with advocating for fair wages, safe working conditions, exploitation of labour, etc., but they sure do mean a lot to Canada's "progressive" elites. This is why the core support for the NDP, a party allegedly representative of the working class, is found in the hearts of the nation's major urban centres, places where you won't find working class culture at all. Places that do host working class culture tend to vote blue.
Returning to the interview, Peter Brimelow used the term "Hitler's revenge" to describe the psychosis of the pro mass-immigration movement and I think he's right on the mark with it. "Hitler's revenge" is the psychological trauma left in the wake of the genocidal practices of the Nazi regime during WWII that the west overcompensates by going to the opposite extreme. To understand this you have to acknowledge race and that the west is, at least for now, overwhelmingly white. To show that they are nothing like the white supremacist, genocidal Nazi regime that they so vehemently fought to defeat the west threw open its doors to non-white immigration thus inviting their own genocide of sorts, both culturally and racially, by nursing a situation in which they, the white majority, will become minorities in their own countries.
I think both situations are nefarious because both are an attack on a people whether that attack is intentional or not. Balance is needed in the immigration system so that the host population is not threatened with displacement or extinction by an alien force be that force invited or otherwise. Canada is a nation with a history, language(s), and a culture that is preserved in its people. Replace the people and you lose all of that.