Hi Bayou21,
We'd like to clarify this a bit more and, hopefully, this can help get this issue sorted out.
You do not need to purchase anything to recover your media. However, since the music and home videos were originally stored on your iMac, and synced to your iPhone, those items only lived on those two devices.
It sounds like you are paying for iCloud storage, and you believed that the music and home videos were stored through iCloud. Items can be stored in an iCloud backup or stored in realtime through iCloud. Check out this resource to learn what is included in an iCloud backup: What does iCloud back up? As you can see from this resource, Music and videos synced and/or stored in the Music app or the Apple TV app are not part of those backups. If your home videos were stored in the Photos app, those would have potentially been stored in iCloud if you enabled Photos in iCloud on your device. The option to save those videos from Apple TV is not available.
If you'd like to look at some of the information that is stored in realtime, you can get a good idea by visiting the iCloud website.
We hope you're able to recover these missing items from your backup, as it seems like that may be the best option for your situation. If you'd like to check into any other possible options, Contact Apple Support may be a good next step for you.
Have a great rest of your day!