Files with the extension .BSF are associated with 'Blu Ray' a media format utilised by Blu Ray optical discs and players.

.BSF files are HD Video files in the .BSF format.

The discs are the same in appearance to regular CD's/ DVD's, but are used for the storage and play-back of high definaition video and data. Blu-ray takes its name from the blue/violet laser used to read the discs.