Perhaps the worst of it is that the lady comes across as a caring 'expert' and SOME of what she's saying is true (like how to identify the different feathers of the wing etc...). I'm honestly surprised that as recently as 2008 anyone was still advising one sided clips. I also think a lot of people who don't know better would probably feel a one sided clip was 'kinder' since it wasn't both wings not realizing it throws them severely off balance. I'm honestly surprised anyone was advising one sided clips as recently as 2008! In probably the past 5 or so years, it has really been discussed and the general consensus of the avian community reached that birds shouldn't be clipped before becoming proficient fliers either, as it is likely they will never be able to learn later on. This video offers 2 suggestions that are now considered outdated/cruel and should be removed.
And just a word as someone who clips my bird- I notice even when 2 or 3 flight feathers have grown back on one wing and not the other, Kiwi's balance while doing his flapping exercises is thrown off. He's so good about clipping at this point, I pretty much clip them off as soon as they grow in instead of waiting for a bunch to show up so his wings are always evenly clipped.