You can always click on "transcript" to read it rather than watching the video. In a (large) nut shell it says:
ectins are to blame for the great “white kidney bean incident” of 2006 in Japan. One Saturday evening, a TV program introduced a new method to lose weight. The method was simple: toast some dry raw white kidney beans in a frying pan for three minutes, grind the beans to a powder, and then dust it on their rice. Within days, a thousand people fell ill—some with such severe diarrhea and vomiting they ended up in the hospital. Why? Lectin poisoning.

Three minutes of dry heat is not enough to destroy the toxic lectins in kidney beans. If you don’t presoak them, you need to boil large kidney beans for a full hour to completely destroy all the lectins—though if you first soak them overnight, 98% of the lectins are gone after boiling for just 15 minutes, and all gone by half an hour. And indeed, when they tested the white beans, toasting for three minutes didn’t do a thing; no wonder people got sick, whereas 95% of the lectins were inactivated after boiling them for three minutes, and completely inactivated after ten. Evidently, “’Do not eat raw beans’ is a traditional admonition in Japan to [avoid] intestinal problems”—and now, we know why.

While canning may completely eliminate lectins from most canned beans, some residual lectin activity may remain in canned kidney beans—though apparently not enough to result in toxicity. And ironically, “[l]ow doses of lectins may be beneficial by stimulating gut function, limiting tumour growth, and ameliorating obesity.
Interest in the purported “antitumor effect of plant lectins” started with the discovery, in 1963, “that…lectins could distinguish between [cancer cells] and normal cells.” Researchers at Mass General found a substance in wheat germ—the lectin in whole wheat—which appeared “to be tumor cell specific”—clumping together “the tumor cells, while the normal cells” were left almost completely alone. So specific that you can take a stool sample from someone, and based on lectin binding to the colon lining cells that get sloughed off into the feces, you can effectively predict the presence of polyps and cancers.......

.....And, what these researchers showed, for the first time, is that the lectin in fava beans could take colon cancer cells and turn them back into looking more like normal cells. Here’s the before picture: cancer cells just growing in amorphous clumps. But then, here’s those same cancer cells after two weeks exposed to the fava bean lectins. The cells have started to go back to growing glandular structures, like normal colon tissue. Therefore, dietary lectins, or putting them in a pill or something, “may slow the progression of colon cancer[s],” potentially helping to explain why dietary consumption of beans, split peas, chickpeas, and lentils appears to “reduce…[the] risk of colorectal cancer,” based on 14 studies involving nearly two million participants. Okay, but what about cancers outside the digestive tract?