This specific file title, Enemy At The Gates -2001- BluRay 720p 900MB Ganool,
To save precious megabytes for video quality, the original 5.1 Dolby Digital or DTS surround sound tracks from the Blu-ray were downmixed into highly efficient stereo audio (usually 2-channel AAC). This kept dialogue crisp and sound effects clear on standard TVs and laptops without wasting space on multichannel audio tracks.