Like other TV Providers, BT go to great lengths to protect their content and prevent it being copied or pirated. Not only to protect their revenue but also to comply with their contracts with the content providers who insist on very high levels of security.
It's not possible to copy HD films, TV, recordings or other content from the BT box.
It is possible to record some SD programmes and films to a hard disc, Blu Ray or DVD recoder via the SCART output if you have a box with a SCART output (T1000 or T2100]. Check though as some programmes including BBC broadcasts, use copy protection to prevent copying via SCART.