When you watch a YouTube video, both the owner and YouTube can access information regarding what parts of the video you watched, on what device you watched it, and tie this information to your account if you're logged in.
#Should i remove macx youtube downloader mp4
If you have an iPod or a multimedia player that's not compatible with YouTube, then you're best off first converting the videos to MP4 or the music to MP3.
By saving a backup of the video locally, you ensure that you'll always have access.