I probably bit off way too much, starting with trying to build VLC. I managed to get a package out of it, which so far will only play audio. There are also no graphics in the UI. I wonder if these errors (when running program) indicate anything amiss in the VL7 base?
libpng warning: Incompatible libpng version in application and library
libpng warning: Application was compiled with png.h from libpng-1.2.37
libpng warning: Application is running with png.c from libpng-1.4.1
Edit: I get the same errors if I run a pre-built Slackware 13 package.