I wonder what I'm doing wrong.

Hello. I am trying to create a service by combining video and nft using Videocoin.
I read and followed the developer documentation, but when I make a video, it disappears after about two days.
I signed up as a member and have 349 Videocoins in Metamask.
If you live stream or upload a file through the web, you will see the video. I know that it is the end of making a video like this, but I wonder what other processes are needed.

You need to copy and store the video assets transcoded using VideoCoin in your own storage space (such as gcp, aws, ips/filecoin) and use your asset URLs in your nft token metadata.