I remember this video, but I'm not sure if I've ever seen the whole thing. I'm rewatching it in the background now.
You highlight that it is often more effort to dispose of something than it is to just keep it. I think this is a really interesting duality to the disposable aspects of a lot of American consumerism. So much of what we consume is designed to be disposed of, so we have an adjusted view of what is easy to dispose of. There are systems for things like trading in cell phones and game consoles, so these are exempt from the challenges of disposal. Many cities have curbside trash pickup, but they limit what you can throw out to whatever fits in your city-issued receptacles or bags. So this creates a deadzone in between "things that fit in the trash can" and "things with systemized trade-ins." Stuff in this deadzone just languishes in the house or apartment for years, especially if it's "still good."
Because as much as people throw out, most people still are apprehensive about throwing away something that's perfectly good. This is where the proactivity is required to unload. You have to donate it or have a yard sale, like you mentioned. But the effort it takes to load something into the car and take it to Goodwill or the time it takes out of your weekend to have a yard sale is enough to keep is in the closet or in the garage for years and years and years.
My own eye opening experience was when I was making plans to move out of that apartment in 2020. I was going through my closet and found totes worth of stuff I moved into the apartment in 2016 that I never even unpacked from the move. It wasn't trash or anything - it wasn't anything that warranted throwing out - but this was a big Rubbermaid tote in my closet that took up the entire footprint of said closet which I had just worked around and piled things on top of for 4+ years. I started looking around the apartment, which had a lot of "out of sight, out of mind" storage, and found so many things we moved in with and never touched, or things we accumulated as gifts and never used, and I thought to myself we have so much stuff for no reason.
I loaded up my car half a dozen times that day and just donated round after round of stuff. It felt really good to be rid of all that weight. In the more than a year it's been since then, I am always so aware of things that secretly take up space. The pots and pans in the cabinet that we never actually use, the boots and shoes by the front door we never actually wear, all sorts of things that occupy precious space in plain sight but manage to be invisible unless you approach your belongings very critically.
Something I try to do now is to try to imagine everything I care about in to my car, not including furniture. There is something secure and comforting to think, if I needed to, I could fit everything that matters to me in my vehicle and relocate it. This doesn't mean everything I own, because inevitably you will own things that are nice to have but are not truly important, but it helps me keep track of what matters, what doesn't, and what might be able to go into the next donation purge.