> ...why there are so many obese people in these video clips, if food is so hard to come by?

This is generally the earlier stages of such a crisis; as the timeline extends, the caloric restriction will gradually chip away at the obesity, but it takes several years as most of these food scarcity crises are not zero calories per day average, but severely restricted, like maybe half TDEE. Fat is an extraordinarily dense caloric storage medium, so shedding obesity can take longer than most people anticipate at that rate. Most first world HN readers who have 18%+ body fat can eat zero calories for a month and not suffer long-term adverse effects, as long as they responsibly observe refeeding syndrome cautions, and a lot of body fat can leap right back on after the fast.

> Why does there seem to be so many people sitting around? Surely with so much manpower available, there are way to make them productive on a large scale?

Generally this happens when the population still somewhat expects the old status quo to somehow re-emerge, partly because they don't know any better. You usually don't see local currencies, co-ops, etc. self-organize until the knowledge is spread to the right individuals who are fed up enough with the crisis to take the initiative to change.

This knowledge gap is where the Internet can help. A DIY kit for those segments of the population left behind by capital owners, to implement autarky where it makes sense, minimize autarky externalities and adverse positive feedback loops where possible, and interface with the external currency where sensible and practical. Perhaps building tech stacks like local cryptocurrencies, payment systems, co-op logistical coordination (think ERP for co-ops), etc., that can be stood up within days of a community deciding to disconnect by firing up free tier cloud instances, and optionally, tech stacks/procedures for re-integration should they decide to do so later. Ideally, these stacks are auto-maintaining and administering, eliminating the need for a staff of administrators or bureaucracy until the locality that disconnects reaches about 20,000.

Open source blueprints for building automated chicken coops that start from basic designs and slowly let adopters build into fully-integrated vermi-, aqua-, humanure-culture reactors, outputting valuable proteins for the cost of sweat equity, mostly scavanged junk, and modest purchases from hardware stores, then time, bacteria, air, soil, rain, and solar thermal energy. DIY preventative medical procedures, basic first-aid equipment, etc. DIY food forestry, which can be started with machetes and shovels initially. DIY styrofoam and plastics recycling, into insulation and feedstock to create community-wide goods like cups/plates/etc. while continuously improving energy efficiency from discarded goods. The challenge is to go as low-tech and scavenging as much as possible, leveraging high-tech knowledge, then get that information into the hands of people in the form of actionable first steps to encourage them to take a small risk and build upon initial successes, and get them out of the mentality of a currency-based exchange as the current system has failed them and won't materially help them anytime in the foreseeable future.