That is strange about the subtitling. Brenda from Bristol speaks more slowly than the others in the clip, too. Or perhaps the subtitler started, became distracted, submitted the work unfinished?

Reason and I have been watching parts of a so-called mastercrafts series hosted by Monty Don, thanks to YouTube and the BBC. (Stained glass has been of considerable interest.) If a US-based child can understand the varieties of speech of the craft participants without subtitles, I hardly see why "Brenda from Bristol" would need subs. (Granted, Reason doesn't understand "viable" and "industrialization" without my gloss, but that's lexicon not dialect.)