Pagelossing this before I continue:

This is probably the last thing I'll say on the subject, mainly because I don't want to get in a stupid back-and-forth argument with people just repeating things and yelling at one another, but I still think it's very important.
The fact of the matter is that saying that something is "late" and nothing else is incredibly dismissive. It's the same as saying something along the lines of "I believe a good number of people have seen this for this video to become irrelevant," or just something as simple as "I've seen this already and it doesn't matter anymore."
What people have to understand that a video's age does not determine its relevancy, as, even with videos that are two to three years old (and when I mean videos I mean pretty much every form of media), there will
still be people that haven't seen it yet. If you've already seen it and it doesn't interest you, instead of telling the OP you've already seen it, which is stupid and pointless, you don't really have to say anything at all. Better yet, something along the lines of "wow I remember this, this was so funny when I first watched it haha" would be better.
The problem isn't the comment itself, it's the context and implications behind the comment, and how it's been perpetuated so violently throughout this community that nobody sees it as a problem anymore. It's created this mentality, this 'unspoken rule' that you're only allowed to post something if it's new, otherwise people will just disregard it completely. It really has to stop.