This is a very insightful piece and certainly sounds a wakeup call about a situation I hadn't thought about. I would like to add a couple of details.

1. The presenter makes a good point that this scenario is very unlikely..However, there would be more problems than he mentions. Canada has a housing shortage as it is so finding accommodation for "milllions" of Americans (or anyone else) would be a real challenge. We would probably need as many shipping containers for people as for guns. (Funny thing here, Canada has managed to accumulate a surplus of shipping containers because we import most things in containers, but export most things in bulk).

2. Americans who anticipate such and event should consider opening a Canadian bank account in one of out Canadian banks in the U.S. (TD, RBC, CIBC, etc.) The Canadian dollar and coins (except pennies) are the only legal currency in Canada. Most Canadian businesses accept American dollars as a courtesy and do the exchange because they want your business. Our banks can accommodate this at the numbers that tourist season brings, but if the influx is much greater than that it will be a problem. American credit cards, based in what will be a war zone are unlikely to get you far.

3. Felonies are different in the U.S. than in Canada, and immigrants or refugees (asylum seekers) will be judged by Canadian felonies, not American.

4. You will not be able to get Canadian health care immediately until you have established residency in a province or territory. Be prepared to pay for health care (there'e that Canadian # bank account again).

5. NATO using Canada as a staging ground is a natural. We always have NATO troops and air forces training here because we have a commodity that is scarce in Europe - space, millions of uninhabited hectares of it. It is ideal for tank, artillery, bombing and mock dogfights over nobody. So, NATO is already here and trained on North American territory. Most Canadians (and Americans) are not aware that Britain added 30,000 troops to their BNA (Canadian) contingents during the American Civil War. nobody noticed them.I understand that NATO troops also train in the US, so they are aware of American conditions.

As I said, this is a thoughtful presentation and we hope that the lessons learned in the American Civil War are clear enough that an insurrection would be unlikely.Keeping it unlikely is going to require, patience, education, and dialogue.

Yes, we have enough of our own issues to have to put up with theirs too.

. . . had my number come up, I would have :

[en.wikipedia.org]

ymmv