Cloud Storage for Videos

I have more than 5 Terabytes of video files. Currently stored on a Synology NAS. I want to backup to the cloud.

However, video storage is not a natural fit to neither "cloud disk" (Google Drive) systems or "cloud backup" systems (CrashPlan) because:

• Data is written once and rarely used.
• There are no file revisions.
• Delete should be prohibited.
• Modifications (viruses, ransom-ware) should be prohibited.

So, my question is: Is there a write once, read only cloud storage, specifically one working with Synology Cloud Sync?