Thanks for reaching out to the Apple Support Community. I understand you've been unable to download music videos to your iPhone and I'd like to help. You were off to a good start when you restarted your iPhone, but if the issue persists I'd recommend signing out of the iTunes store entirely and then back in to establish a fresh connection to the server.
To sign out you can tap on Settings > iTunes & App Store, then tap your Apple ID and select "Sign out". Afterward, restart your phone again and sign back in and try to download again.
- Tap Settings > iTunes & App Store.
- Tap your Apple ID.
- Tap Sign Out.
- Go to Settings > iTunes & App Store.
- Tap Sign In, then enter your Apple ID and password.
Sign in with a different Apple ID on your iPhone, iPad, or iPod touch
If the behavior persists, or you run into any trouble we're here to help.
Best Regards.

