I need to make a small correction in a video I uploaded to YouTube. Googling shows that this is not possible. However, I remember seeing it done before. I posted a comment on a video saying that a certain part of the video was missing. I got a reply back that it was fixed, and when I went to see the video again, it was changed. How was this done?
Videos can not be replaced, but they can be edited.
Quote from YouTube Help (Replace or delete your video):
You can’t replace a video since any new video uploads will get a new URL, but you can make changes to the existing video.
It should't be possible and I hope it's not. The reason is simple: Let's say you are uploading one really interesting video that goes viral with few millions views and then you are changing it to something completely boring. Wouldn't it be a little bit confusing for the new viewers on why exactly this video got so many views?
I think you can make few tweaks to the video from what YouTube offers you and maybe the editor could help, but I'm not a YouTuber to know anything more.
In my opinion, probably the issue is not that YouTube would or would not allow video replacement but it’s the original content that can't be altered. By allowing such ability, it would contaminate the authenticity of original content.