a file named /usr/share/aclocal/bmp.m4 is missing after installing beepmp the beepmp-midi plugin source http://mitglied.lycos.de/mldoering/bmp-midi.tar.bz2 includes such a file. bmp.m4 is needed to make the compile process for custom Beep Media Player plugins possible.
This file is not in the BMP 0.9.7 tarball, so it can not be an error in installing the program. All plugins currently in the tree can deal with this situation (and this list is growing larger by the week); I feel plugins should have bmp.m4 in their source tarball if their build process depends on it. Plugins depending on bmp-midi for their bmp.m4 file is an unwanted situation. If you expect a dire need for this in the future, please submit a bug upstream so it's added to the BMP CVS and will reach us with the next release.