This is directed not only to you but to a LOT of people that have the same weird attitude. The weird part is that you almost deliberately avoid stating a reason for the feature not to be added. You said two things:
"I really don't see any reason to add it."
This is an answer to the exact opposite question. We aren't asking you for a reason to add it, we're asking for a reason not to add it.
"The idea is that I don't want mirc to become just another multimedia program."
How adding something ("add" means old features + new features), changes mirc from your favorite IRC client to "just another multimedia program"? More the point, how adding something hurts the already existing functionality?
Yet such reason surely must exist, and it must be good, since you're willing to stick to older versions (if video support is added) and deprive yourself of other useful features of newer versions. So, I really wonder, what is it?