You will want to upload the video to YouTube and change the privacy settings so that it is "Unlisted." Once the upload has completed:
- Add it to a YouTube playlist.
- On plug.dj open up the Playlists panel and go through the Import from YouTube steps.
The video will still play on plug.dj, but people will not be able to search for it on the YouTube website. You may want to consider removing the video from YouTube after your turn to ensure that it will not be seen by anyone again.