That's odd, when the system prompts a duplicate upload message, it means it already exists. Try signing out & back in or use a different computer. If the video shows, make sure that your browser is updated, clear cache & cookies, & restart device. Hope that fixes it.
This means the video you've uploaded already exists within our system. You can try editing the video and uploading it again. For example, changing the video length (e.g. by adding extra frames by using video editing software) or compressing the video: https://yt.be/help/kTKB
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