freevo currently has a dependency on >=dev-python/twisted-1.0.7. >=twisted-2 do not provide everything previous versions of twisted did (the package was split). The dependency should probably be "|| ( ( >=dev-python/twisted-2 dev-python/twisted-web ) <dev-python/twisted-2 )". Got this by grepping the source for imports and a very brief test, but I am not sufficiently familiar with the package to test if it fully works with newer twisted at all, so please check if the dep should be something like "<dev-python/twisted-2" instead.
Fixed them at =twisted-1* to play it safe until someone can actually maintain it.