: Likely the start of "Baixar" (Download) or "Baixandofacil" , a common prefix on file-hosting directories.
: Often denotes "Legenda" (Subtitles), commonly used on Portuguese or Brazilian fansub sites. You have requested : House.MD.S03E09.MP4.LEG.Ba...
If you are looking for the technical "piece" of information hidden in the filename: : The show, season, and episode number. MP4 : The video file format. : Likely the start of "Baixar" (Download) or