Solution to the AC3Filter problem
If AC3Filter is not shown in BSPlayer, you have to add these two lines to the file
bspfilters.dat in BSPlayer directory:
AddFilter {AEFA5024-215A-4fc7-97A4-1043C86FD0B8},MatrixMixer
AddFilter {A753A1EC-973E-4718-AF8E-A3F554D45C44},AC3Filter
If you don't have the file bspfilters.dat, then you should rename bspfilters.sam ---> bspfilters.dat.
You can also download the working file here:
http://www.hot.ee/reameez/bspfilters.dat
I hope BST adds this to the next version automatically :)