i also think... depending on the amount of energy a parent puts into the whole episode depends on how much 'harm' it causes.
if the parents go on and on about it endlessly to everyone who listens or gets too detailed into explaining the program to the child... that's where the longer term effects happen.
if the parent acts like it's no big deal and let's the child's own feelings etc be their own... then often they forget about the incident quickly.
but every child is different and comes from a different enviroment which will cause their experience to be uniquely theirs.
edited to add: of course the actual video shown makes a difference as well. some 'shots' (no pun intended) would be more detrimental than others.