If you indeed permitted BS.Player upon its installation to also "internally" install its preferred codecs/filters, AC3Filter has already been installed on your system. You can check by having a look inside BS.Player's installation folder, where you will find a folder "AC3 Filter". If there is no such folder, you didn't allow BS.Player to install its preferred (and needed) codecs/filters, but you can still do so, using "codecmanager.exe", which you can also find inside BS.Player's installation folder.
If you find that the folder "AC3 Filter" is there, please load the TS XviD.avi file and then rightclick > Options > Filters > Advanced.
There you see the filter(s)/codec(s) which are used by BS.Player for playback of the file loaded. Clicking on the small [+]-signs in front of the codec(s)/filter(s) shown, will reveal further info and access to them.
Please inform us what filters you see. (Make sure to also click on "Source" and let us know the info shown there.)