Where do you store your media?
Are you using the default video share provided by Synology?
If so, this is the root problem. Synology claims it whether their software is installed or not.
If you can create your own shares for your media and move it there, you will be free of this unwinnable battle with them.
I am providing this FAQ ref as I do not know how you’re currently configured.
Might you care to share your share structure?