Really depends on the way you watched it, also if you paid real attention to it or were only passively paying attention while doing other stuff, and I guess age also plays in to it as well, the younger the better.
Equally a big one is if you already knew other languages, the brain learns how to interpret the subtle nuances in speech better with each language you know, but it has diminishing returns obviously.
I learned a lot of French and Japanese speech patterns without knowing a single bit of either language. German as well actually. I still don't know shit about French despite it being one of the major secondary languages in the UK. (fucking orgy sounding ass language)
UK foreign language education is probably on the same level of terrible as Japans is.