Didn't watch all of it, but that does look a good tutorial, very thorough with several of the points I find I often have to talk to people about.
For cord...starter cord for mower or chain saw. Cheap, tough, meant to be abused and not to stretch. I do not like paracord.
To help with keeping the cord on the drill, you can use a knife to take shavings so the drill has a subtle waist. On a 1.25" diameter drill the middle of the waist might be 1 to 1.125" and if the drill is 8-10" long, the shavings to create the waist occupy about 75% of the length. If you can keep it all controlled without this, that is better, but this is something to try if you keep running the cord off the top or bottom of the drill. This tends to be driven by not moving the bow parallel to the ground, but every little can help.
Black Poplar bark makes a remarkably good bearing block. Not super long lived, but it holds up lots better than you would expect given how soft it is. The bark is highly rot resistant and can be found at the site of a fallen tree many years after the tree fell. For more deliberate and longer lasting kit, harder bearing blocks are good. Some people can find stones with dimples. I made one from a bit of dead standing hornbeam once, not easy to work cut, but it worked well as a bearing. I would imagine that box wood would be good too.