Horse hair is what I have used. Cornish lime has it pre made with coarse and fine hair. If you are not using pre made you can use NHL 5 for coastal wet areas or one NHL 2.5 - 3.5 with 2 parts sharp sand & 1 part soft samd for lime stone pointing.
Great vid pal, hats off to the guy for having a go though!! Lime work is a heavy priduct to shift about and long wait times on the curing, can see sorta why its phased out, but for older buildings its a belt an braces aproach but deffo agree that you have to have peoples budgets in mind as its reet expensive stuff. He was bang on with the scratch coat, use bits of broken laths to form diamond shapes in the scratch. Have seen people use comb scratchers for lime and still make diamond shapes though 🤔
he didn't go to the bottom with the scratch as he's got 12 tubes of grip fil to put skirting boards on with , get'em nice and level no gaps 😂 , Thanks for watching these videos so we don't have to 😎