For anyone else who was curious about it, you can find the documentary on their youtube channel and it has working English subtitles!
Edit: actually scratch that, Piped has subtitles too, just click on the three dots and you'll find the English Captions option there too.
OOhh, I didn't notice! The are English CCs/subtitles on Piped!
My bad, didn't see the options, that's why I looked for another source in the first place.