Hi, I'm no expert (not having either a BV5 or a Macmini ) but have been looking at getting a macmini to connect to a soon to arrive BV7. Seems there are issues with the age of the macmini you have - pre 2009 a DVI-VGA adapter seems to work fine (combined with a coaxial for the audio) post 2009 I think you might have to get a mini-displayport to VGA cable, and then a VGA to Composite converter. Have a look at these threads thread thread2 might help.
Edit - sorry just realised you have a macbook mini not a macmini - but ? above may still be of use
BS3200 BV7 BV3 BL8000 BG4000 BL4500 PC2 BG5500 MX4002