XviD/DivX apparently share several public symbols ("grep divx
/usr/lib/libxvidcore.so" to see for yourself). gst-register loads and
unloads each plugins. Unloading is apparently unimplemented. Therefore,
xvid will overrule the divx symbols before divx can load itself, or divx
will load symbols which xvid wants to overrule. The one makes the other crash.

xvid will segfault in xvid_init() if divx was loaded first. divx versions
etc. will be overrules by xvid and the version check in the divx plugin
(because divx4linux isn't ABI/API stable) therefore fails if xvid was
loaded before divx, and the plugin fails to load.

I don't know how to solve it, apart from kicking the hell out of the xvid
people for screwing up so badly (they overrule divx symbols, but not the
other way around). Anyone knows a better (working ;) ) solution for this
issue? Even if we'd implement plugin unloading, we still wouldn't be able
to load xvid/divx plugins in the same pipeline. :(.