A shit subject but someone's got to cover it!
The use of urine for various things was unsurprising. Not that I knew about it, but there aren't a lot of sources of organic chemicals in the pre-petroleum world. We still use urea to treat diesel emissions, though we make it out of petroleum instead of piss now.
Not just medieval world, back in the 50’s and 60’s it was still being used for stain removal and as a mild disinfectant for wounds.Urine had all sorts of uses in the ancient/medieval world.
Tanners also had a reputation for stench.