My partner has just headed out, going to the local library. She was carrying more in both weight and volume than I did on either of my last two overseas journeys for personal travel.
EDIT: Watching the video, he seems to have way more stuff than me in some respects - e.g. the toiletries, electronics, and medical supplies. But, he has less clothing than me. I prefer to take five days clothing in the bag, including one spare sweater, one pair of spare trousers, and one pair of spare trousers (he only had the last). This takes up the majority of room in my bag, and other stuff fits around it. I haven't used packing cubes or other bags within bags, and wonder if I should. I tend to end up in countries where self-service laundrettes are not a thing, and managing getting clothes washed if I'm moving on occasionally can require some planning. (And paying the lady next door in Isfahan to wash and dry my clothes for me, etc.) He also has an umbrella. In normal life I typically use large umbrellas, and the small ones I've bought in emergencies have been ... cheap and didn't last. If there was a light but strong small umbrella that gave good coverage that would help. I'm guessing it will be like bicycles - strong, light, cheap - you can have any two of those but not all three.
I note he has Bose non-noise cancelling headphones. I usually use over the ear headphones, but they take up space. For my last trip I bought a pair of Sony MDR-XB50AP headphones, and I was impressed with the sound quality for the price, and the extent to which they excluded external sound. These will definitely be my choice of headphones for future trips.
I didn't see him pack a towel. I definitely take one, and don't feel right taking a hotel towel to swimming pools etc. Having recently greatly enjoyed a pool with a poolside jacuzzi
, swimming while overseas is going to be something I want to do more. Like the guy in the video, I take shorts and t-shirts in case of exercise, and a very small and fast-drying towel. In a hotel room without a towel recently I washed, shook water off, and then walked backwards and forwards in the room until I was dry enough to dress. I had a personal towel, but I find that for one-bagging, I definitely want to avoid 'damp stuff' in general. My personal washing thing in place of a sponge gets damp, but it fits in an external pocket of my bag.
Sorry if I've gone off on a stream of consciousness thing here.