How would films like this be consumed in the 30’s? Would it be shown in theaters before a feature film?
Just hypothesizing, but either GM might distribute these and have showings for staff as part of training. Almost certainly not for the engineers that already learned this but perhaps sales staff so they could better explain the mechanism and benefits to buyers.
The OP was asking how people might watch a video like this, not who is watching it. In 1937 broadcast television was relatively new and few people owned a tv. For example, the wikipedia page for TV in 1937 notes that by the end of that year 2,121 TVs had been sold in England:
My understanding is US conscription only restarted for WW2 in 1940.