The BBC must deliver an online TV catch-up service that lets users of all computers download programmes, the corporation's regulators have said.
It comes after the BBC said a download service for Mac and Linux users was not 100% definite and would depend on cost.
All downloaded video content from the BBC contains digital rights management (DRM) technology to prevent the programmes being copied and to ensure the content is only available for 30 days.
The BBC says the DRM offered by Microsoft - which is not available for Linux and has not been licensed from Microsoft by Apple for Macs - is the only solution at present.
Perhaps the BBC will consider Adobe's DRM solution, since iPlayer is going to be rebuilt in Flash