As stated in the installation instructions the path where the file is installed can't be changed after compilation. So when exeinto() followed by doexe() is called in src_install() the installation basically is screwed and will not work. To avoid this there's a configure option available called "--with-plugin-dir=..." which solves this issue. I modified the ebuild and added this to make the plugin work, see the attachment I'm going to attach in a minute.
Created attachment 136969 [details] Modification of the original ebuild
I really don't see what you fixed here, sorry. <snip> --- swfdec-mozilla-0.5.4.ebuild.orig 2007-11-24 19:13:58.000000000 +0100 +++ swfdec-mozilla-0.5.ebuild 2007-11-25 12:27:57.000000000 +0100 @@ -1,6 +1,6 @@ # Copyright 1999-2007 Gentoo Foundation # Distributed under the terms of the GNU General Public License v2 -# $Header: /var/cvsroot/gentoo-x86/net-www/swfdec-mozilla/swfdec-mozilla-0.5.4.ebuild,v 1.1 2007/11/24 18:13:58 pclouds Exp $ +# $Header: /var/cvsroot/gentoo-x86/net-www/swfdec-mozilla/swfdec-mozilla-0.5.3.ebuild,v 1.1 2007/10/20 10:51:58 pclouds Exp $ inherit multilib versionator @@ -19,8 +19,9 @@ RDEPEND="" src_compile() { - econf --with-plugin-dir=/usr/$(get_libdir)/nsbrowser/plugins - emake || die "emake failed" + econf --with-plugin-dir=/usr/$(get_libdir)/nsbrowser/plugins || die "Couldn't run configure" + + emake } src_install() { @@ -29,3 +30,4 @@ insinto /usr/$(get_libdir)/nsbrowser/plugins doins src/libswfdecmozilla.la } + </snip>