There are vital differences between your anecdote and the punch bag.
In your situation you were releasing anger in a positive act of helping to rebirth a social centre, that is turning a domestic residence into a spiritual centre. You were helping a group of people to do this positive thing. When you went home at the end of the day the house was a little bit more dead and that meant the spiritual centre was a little bit closer to being alive.
What you did was a physical demonstration of how anger energy can be turned into a positive expression that speeds up the natural cycles of life. You were mentally participating in those cycles and the process itself commented upon the fact that death is a part of life and even when a house is derelict life must go on.
The act of renewal, especially when placed in such a spiritual context, can be viewed from a deep and subtle perspective that easily explains why it released so much aggression and refreshed your psyche.
Punching a bag full of sand repetitively by yourself achieves nothing and shows little. If you are mentally in a state where such exercise is about discipline and physical improvement then this is not a problem. Using it as a valve for pent up emotion is unsatisfying and more likely to lead to frustration.
How does this inform the video game violence question? Simple a video game should not be used as a crutch for emotional release. They can clean the mental screen through simple, repetitive, action-reward cycles that may not be available in the wider world. If you sit down with a video game just to relieve the very particular frustration of feeling stuck in a rut, or not getting any where it could be quite therapeutic, but trying to cope with deeper anger issues this way is not appropriate.
A subtlety I doubt is addressed within any report on violent video games as we tend to view all "anger" as the same "anger" irrespective of its source. Its been documented a couple of hundred times how social and psychological experimenters tend to find whatever it is they're looking for in any given study and yet no major collapse or resolution in their questionable methodology is implemented because it would require an academic perspective too radically different from any remembered in the majority of human culture. So I don't expect it to change any time soon.
I give any sociological report the respect it deserves. None. And less than that if it claims to be conclusive.