It may help you to consider the sentence without 'being'. (Thanks for using such a colourful example by the way!)
Getting sexual pleasure from physical hurt.
Physical becomes an adjective describing 'hurt', rather than an adverb describing 'being'.
The direction, so to speak, of the hurt is no longer clear (what is done to whom). Who has to be hurt for the masochist to gain pleasure? It is not clear. It could be other people, it could be the masochist themselves.
Knowing what a masochist is, we know that would be an inaccurate definition. Mascochists are specifically people who enjoy pain inflicted on themselves. "Being hurt" places the masochist in the, ahem, passive position.* The action is being done to them.
So, what you are seeing when you look at these constructions with being verbed (Subject + be + present participle of "to be" + past participle) is the present continuous tense in the passive voice.
I am being tortured [by someone else].
He is being tortured [by someone else].
We are being tortured [by someone else].
etc. The torture is being inflicted, happily and willingly or not, on the subject of the sentence by an often implied and sometimes explicitly mentioned other person.
(*One might almost say subordinate, if one wanted to belabour a pun in a way that is grammatically misleading).