[Arnt]

How?

Say the BBC made a great series in 1978 and paid the composer of the music for enough rights to air it in the UK, but not for media which were not yet invented at the time. The composer is now dead, the heirs moved to NZ and Italy, the will (written in 1982) doesn't make quite clear which heir inherited the internet rights, and none of the heirs really care to pay lawyers for the sake of a £500-1500 sale. How do you propose to arrange acquisition of the rights?

This isn't even very farfetched. A lot of old contracts were written without consideration of the streaming possibilities that eventually ensued. BTDT.