Problem re. DivX 5.1 should be solved in last nightly version 501.
You already have build 500, so it's just an upgrade as follows:
Just place (or directly unzip) the two substituting files and one
additional file of build 501
http://www.bsplayer.org/dlfile.php?fname=bsplay.zip in BSPlayer's existing installation directory (overwriting/replacing the existing files).
Edited: just forget about the
additional file, it appears to be no longer included!)