The use of the Canadian dollar has been part of the platform of the PQ for decades.
Some of the Oui signs in the 1995 referendum even had the Canadian loonie on them:
https://www.google.ca/search?q=oui+e...biw=1536&hl=fr
Now, I've always been 50-50 on this idea.
On the one hand, in spite of what a lot of people say, it's actually totally false that a sovereign country can't use another country's currency. (And it doesn't need permission from the latter country.)
There are quite a few countries for example that use the US dollar as their national currency. It would be even easier for Quebec to do this with the Canadian dollar than it is for some of them because there are already billions of Canadian dollars in circulation in Quebec. And everything in Quebec already uses the Canadian dollar as the base value for everything.
That said, where PSPP is not completely wrong is when he talks about monetary policy and national interest. If Quebec (or some in Quebec) already feel that Canadian monetary policy does not serve Quebec's interests at the moment, it won't serve our interests more if we are a different country. I doubt we will have a say in how the Bank of Canada manages the Canadian dollar, which in that case will be all about the interests of Canada-sans-Québec.
So in that sense, the current minister who is a member of the CAQ might be right that the US dollar could be a better option given the relative stability that comes from the fact that its management and value is driven by more purely mercantile and economic considerations (since we're talking about the US) and probably and incredibly, not quite as political as decisions affecting the Canadian dollar are.