Earlier quoted context omitted.
From the video they have on youtube, Arnold has over 200bpm and the kid at the end has a 0bpm. That's a pretty useless territory.
That video was just a mock of our product. If you would like to see the results of the performance of the models, have a look at the slides we made for the project (at the bottom of the post). The best performance we got was about 0.7 r.
0.7 r is a bit optimistic I would say. We only got 0.7 for people we have been able to train on. For completely different people it learned nothing with audio spectrograms. I speculate that convolutions on raw audio would be better.
Estimation from video seemed much better. There we actually got 0.5 r on unseen people, which I find very promising.