As someone who has used propranolol on and off over the past few years, the thing that intrigues me here is that propranolol works well in this instance due to crossing the blood/brain barrier as opposed to other beta blockers that do not.

The use of beta blockers in anxiety is commonly associated with reducing the effects of stress on heart rate and blood pressure, not necessarily on affecting the brain directly which appears to be happening here. That is, beta blockers are usually a band aid rather than a fix, so this discovery is exciting.

(As an aside, if you suffer from unusual levels of physical response to certain stimuli while intellectually remaining calm or indifferent, propranolol may be worth investigating for you as it has helped me a lot. At your own risk, of course.)