finetune bit/distortion weighting factor used in motion estimation, the old coeffs where finetuned relative to incorrect mv_penalty tables which where then fixed later but the coeffs where not
this _may_ fix the long standing blocking artifacts, but may also introduce mudding artefacts theoretically, so please tell us if u stumble across any so we can either fix them or export this variable so the user can change it

Originally committed as revision 3189 to svn://svn.ffmpeg.org/ffmpeg/trunk