Can I Disable Video iCloud Backups in Camera Roll?

No. There is no way to disable only video iCloud backups in Camera Roll. You can disable both photo and video backups in Camera Roll. But, if you want to backup photos and not oversize videos, then it is not possible.

If you want to disable iCloud backups in Camera Roll, then open "Settings" on your iOS device and tap "iCloud". Tap "Storage & Backup" located at the bottom on the screen and tap "Manage Storage". You will see all details of your device. Tap on your current device under 'Backups'. Move the slider from right to left to turn OFF "Camera Roll". Tap "Turn Off & Delete" button. Just make sure that your current Camera Roll has been totally imported before clicking "Turn Off & Delete" button. Videos do not go to the Photo Stream, so you will need to transfer them off your iOS device to make a backup copy of them.