The bottle in the first clip was quite difficult to identify, the second was so subtle that I almost missed it, and the third clip is a mystery malt.
It this scene George (Colin Firth) polishes off the bottle of North Port 20 year old Rare Malt which he keeps in his desk like nobody's business and tosses it in the trash. I had to play the clip back several times and zoom in to figure out what brand it was.
This sighting takes place at the 28:50 mark.
The second clip takes place exactly 41 minutes into the film and features three different brands. There is a bottle of Lagavulin (my second favorite single malt) as well as the classic blends Black Label and J&B.
The final clip (from 1:10:35) simply shows George ordering a scotch at a bar and drinking it with one of his students. No mention of the brand and no sign of the actual bottle.