Q: I only want to backup certain files (slo-mo videos) on icloud. Is this possible?

Hi EmilTee,

If I understand correctly you only want to backup your slow motion videos to iCloud when it backs up. When you go here:

1. Tap Settings > iCloud. 
    
   • If you're using iOS 8 or later, tap Storage > Manage Storage.
    
   • If you're using an earlier version of iOS, tap Storage & Backup > Manage Storage.
2. Tap the name of your iOS device.
3. Under Backup Options, turn off any apps that you don't want to back up. When you're asked to confirm, choose Turn Off & Delete to turn off Backup for that app and remove all of its data from iCloud.

Manage your iCloud storage - Apple Support

The option for Photo Library only has a single toggle, so it looks like it is all or nothing, so to speak. You can however import the photos and videos you have to a computer and delete them from the phone to reduce the size of the backup:
 

Import photos and videos from your iPhone, iPad, or iPod touch to your Mac or Windows PC

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