Skrapmetal, Take a look at OnePlanet and Wilderness Equipment bags from australia. They are canvas, (modern colors) but tough as nails. modern packs designed to bushwhack through wait-a-while vines.
as for the vid. Sure, if that works for you. I think its a great skill to know how to improvise a pack if needed, but I like to be able to get stuff in and out reasonably quickly. I'd be a K down the trail by the time he's packed to go. (okay, maybe just finishing my coffee, but you know) No disrespect to Mors but there are a few logical fallacies that he bases his statements on. But he does say that a custom built packframe is better than a store-bought packframe. Well yes, it would be. He makes a big deal of how customizable it is, and compared to old style frame packs, I'd say he's correct, not so much when it comes to a modern pack. Everything he says is basic pack fitting, it works for a modern soft pack, internal frame or external. Although how thats supposed to matter with stretcher carry, I'm beat. I'm sure he's carried heavy loads, but what is heavy to him? What where they carrying?
I think there is a lot of romanticism to old gear, but you have to think that they called brachial paralysis "backpackers palsy" for a reason. how much of that gear was carried in on horseback or by dog-sled. Very few lived fully off the land even in the mountain man days, mostly it was operating from a basecamp, moving light to move fast, but the main camp was not mobile. Even the Lewis and Clark expedition was on an industrial scale to keep the party fed and moving. The stories of guys covering huge amounts of terrain with little kit are remembered because they were so uncommon. Now people do ultra-light trips so commonly its not noticed. Lastly a lot of the old ways are very inefficient from a resource use standpoint. A lean-to that is used for one night, a long fire that is kept burning, all use up more resources than a good tent, good insulation and 50ml of alcohol for cooking. Yes there is an argument to be made for the environmental impacts of plastics, but at the end of the day, most environments cannot handle very many people for long. The acreage required for a hunter-gatherer tribe is quite astonishing.