OBS recordings of YouTube green screen videos lagging.

I'm not even sure if the other videos are slowed down, but I don't think they are (I would only record clips of what I'm reviewing or whatever, in that case), but I have used OBS to record green screen videos, which are placed there to be used by other people anyway (they are uploaded videos of something already in green screen, for you to add to your videos if you want) and even if the recording ends up perfect (YouTube has a habit of pixelating when I try to do this, so it took several attempts to record some anyway) it ends up lagging when I play it back, even if it looked perfectly normal when it recorded.

I have seen some tutorials, and will continue to look, but the only one I can vaguely remember understanding said something about changing a computer setting I don't want to mess with (like my screen size of frame rate), does anyone no a way around this or why it's happening?