Yes, typical dour Scot expression.
I believe that is the only extant imagery of the BHT. In several volumes of Spike's war memoires he does mention that he rated BH as an exceptionally talented violinist. He also states/implies that BH was a slightly dissolute womaniser who never really bothered to make the most of his talent.
From that short clip it does seem that he knew what he was doing with a violin.