I think the (...)'s depend on how they are used. For example, if a guard were to ask a prisoner a question, and the prisoner refused to speak, showing "...." would indicate to the player that the prisoner has chosen to remain quiet.
Also, if there is a cutscene where one person is speaking to another (perhaps the immediate character the player has control of) but you don't want to reveal the extent of that conversation having a couple of instances of "...." back and forth between the two would indicate the characters are talking. This is a good example of when you want the player to know a conversation has taken place but don't want the player to know what was discussed, which could be good for a plot twist down the road. However, this could also be easily abused so it should be done only when the situation calls.
As for "..." within dialogue, I find it appropriate only to some degree. For example, let's say the hero is angry at his friend and accusing him of something, only to stop midway and change his tone and attitude upon realizing it's his fault. The hero's dialogue could go something like:
"It's not my fault, you're the one that hit the switch! Why can't you just man up... sorry, you're right, it's my fault."
But I agree with Strangeluv, too many instances of "..." gets old and tedious and should be used sparingly.