So DaasYochid your saying that its mutar to copy something you already own?
Barring specific, valid limitations in the sale (e.g.) leasing agreements, yes.
How far does that extend? Can only your immediate family use it?How about friends?
I suppose they could borrow the original to use. Rav Belsky was mattir for immediate family members living in the same home.
What about if ts for a music video?
Probably not.
can you post it to a site where everyone will be able to copy it?
No.