Enjoyable video, worth watching the full length version, though I expect folks on this forum would find the info remedial. Around minute 12, there's fantastic footage of a canoe recirculating at a low-head dam - great example for teaching others about this danger.
Also interesting to note that both this video and a Bill Mason video feature a wood/canvas canoe getting destroyed in rapids. A reflection of the ubiquity of w/c canoes at the time of filming? Or just a reflection of ample filming budgets? I can't imagine anyone doing such these days. Ironically, both videos also feature composite or aluminum canoes....but a w/c smashes up against rocks a lot better on film.
Regarding swamping a canoe to rescue someone, I imagine the work-ability of that depends on your canoe's neutral buoyancy to a certain degree. I've discovered that my Wenonah Heron sits with much of the gunnels around the center underwater when swamped - only the stems stick out above the surface, and that's completely empty. With a couple people inside, I don't know that it's paddle-able at all. Maybe enough of a platform to stave off drowning and hope for a rescue, but I bet w/c canoes had a lot more buoyancy? Either way, something worth trying out and practicing!