Search for a smaller act's new music video and you may find it on a channel that is not theirs — 1theK, for instance, which distributes videos for a range of artists. The instinct from outside Korea is to treat that as a reupload or a mirror, and to go looking for the real one. There is no other one to find.
The channel says so itself, in English, in a line that sits under every such upload: 1theK YouTube is also an official channel for the MV, and music shows will count the views from this channel too. That is the whole answer, printed on the post, and it is easy to scroll past because it looks like the rest of the boilerplate around it.
Those descriptions come in two shapes, and it is worth knowing which one you are reading. Most are the standing block: a channel welcome, a link to a live channel, that notice, and the tags. Nothing in it is about the song. Where the credits exist at all, they are packed into the video title instead — performer names, the song, and sometimes a production credit, all on one line.
The second shape is more useful. Some posts replace the welcome with a three-line release card — an artist line, a title line, and a release line with a date on it. When you see that card, the date is stated and you can take it; when you see only the boilerplate, no date has been given and there is nothing to infer from the silence.