Actually, Dick, I think your estimate for the Liverpool Hornpipe You Tube clip was low. Using the tap in on my metronome, I was getting figures for the minim beat of between 76 and 82 with it mostly being around 78 - 79. That equates to a crotchet beat some 13 - 15 bpm higher than your figure.

I usually tap a minim beat when I am playing as I think it makes it easier to maintain a steady tempo, but that is a personal view.