thunar-thumbnailers won't compile correctly.

I am trying to compile thunar-thumbnailers, my intention is for thunar to show thumbnails for the videos that are on my hard drive, but when I try to compile it, I get the following output:Code:bash-4.3# ./thunar-thumbnailers.SlackBuild
thunar-thumbnailers-0.4.1/
thunar-thumbnailers-0.4.1/NEWS
thunar-thumbnailers-0.4.1/mime/
thunar-thumbnailers-0.4.1/mime/thunar-thumbnailers.xml
thunar-thumbnailers-0.4.1/mime/Makefile.am
thunar-thumbnailers-0.4.1/mime/Makefile.in
thunar-thumbnailers-0.4.1/xcf-thumbnailer/
thunar-thumbnailers-0.4.1/xcf-thumbnailer/xcf-thumbnailer
thunar-thumbnailers-0.4.1/xcf-thumbnailer/Makefile.am
thunar-thumbnailers-0.4.1/xcf-thumbnailer/Makefile.in
thunar-thumbnailers-0.4.1/xcf-thumbnailer/xcf-thumbnailer.desktop.in
thunar-thumbnailers-0.4.1/ogg-thumbnailer/
thunar-thumbnailers-0.4.1/ogg-thumbnailer/ogg-thumbnailer
thunar-thumbnailers-0.4.1/ogg-thumbnailer/Makefile.am
thunar-thumbnailers-0.4.1/ogg-thumbnailer/Makefile.in
thunar-thumbnailers-0.4.1/ogg-thumbnailer/ogg-thumbnailer.desktop.in
thunar-thumbnailers-0.4.1/aclocal.m4
thunar-thumbnailers-0.4.1/fig-thumbnailer/
thunar-thumbnailers-0.4.1/fig-thumbnailer/fig-thumbnailer
thunar-thumbnailers-0.4.1/fig-thumbnailer/Makefile.am
thunar-thumbnailers-0.4.1/fig-thumbnailer/Makefile.in
thunar-thumbnailers-0.4.1/fig-thumbnailer/fig-thumbnailer.desktop.in
thunar-thumbnailers-0.4.1/README
thunar-thumbnailers-0.4.1/ps-thumbnailer/
thunar-thumbnailers-0.4.1/ps-thumbnailer/ps-thumbnailer
thunar-thumbnailers-0.4.1/ps-thumbnailer/ps-thumbnailer.desktop.in
thunar-thumbnailers-0.4.1/ps-thumbnailer/Makefile.am
thunar-thumbnailers-0.4.1/ps-thumbnailer/Makefile.in
thunar-thumbnailers-0.4.1/configure
thunar-thumbnailers-0.4.1/tex-thumbnailer/
thunar-thumbnailers-0.4.1/tex-thumbnailer/tex-thumbnailer
thunar-thumbnailers-0.4.1/tex-thumbnailer/tex-thumbnailer.desktop.in
thunar-thumbnailers-0.4.1/tex-thumbnailer/Makefile.am
thunar-thumbnailers-0.4.1/tex-thumbnailer/Makefile.in
thunar-thumbnailers-0.4.1/configure.in
thunar-thumbnailers-0.4.1/config.guess
thunar-thumbnailers-0.4.1/install-sh
thunar-thumbnailers-0.4.1/config.sub
thunar-thumbnailers-0.4.1/missing
thunar-thumbnailers-0.4.1/agr-thumbnailer/
thunar-thumbnailers-0.4.1/agr-thumbnailer/agr-thumbnailer
thunar-thumbnailers-0.4.1/agr-thumbnailer/Makefile.am
thunar-thumbnailers-0.4.1/agr-thumbnailer/Makefile.in
thunar-thumbnailers-0.4.1/agr-thumbnailer/agr-thumbnailer.desktop.in
thunar-thumbnailers-0.4.1/Makefile.am
thunar-thumbnailers-0.4.1/Makefile.in
thunar-thumbnailers-0.4.1/pdf-thumbnailer/
thunar-thumbnailers-0.4.1/pdf-thumbnailer/Makefile.am
thunar-thumbnailers-0.4.1/pdf-thumbnailer/Makefile.in
thunar-thumbnailers-0.4.1/pdf-thumbnailer/pdf-thumbnailer.desktop.in
thunar-thumbnailers-0.4.1/pdf-thumbnailer/pdf-thumbnailer
thunar-thumbnailers-0.4.1/config.h.in
thunar-thumbnailers-0.4.1/odf-thumbnailer/
thunar-thumbnailers-0.4.1/odf-thumbnailer/odf-thumbnailer.desktop.in
thunar-thumbnailers-0.4.1/odf-thumbnailer/Makefile.am
thunar-thumbnailers-0.4.1/odf-thumbnailer/Makefile.in
thunar-thumbnailers-0.4.1/odf-thumbnailer/odf-thumbnailer
thunar-thumbnailers-0.4.1/AUTHORS
thunar-thumbnailers-0.4.1/dvi-thumbnailer/
thunar-thumbnailers-0.4.1/dvi-thumbnailer/Makefile.am
thunar-thumbnailers-0.4.1/dvi-thumbnailer/Makefile.in
thunar-thumbnailers-0.4.1/dvi-thumbnailer/dvi-thumbnailer.desktop.in
thunar-thumbnailers-0.4.1/dvi-thumbnailer/dvi-thumbnailer
thunar-thumbnailers-0.4.1/raw-thumbnailer/
thunar-thumbnailers-0.4.1/raw-thumbnailer/raw-thumbnailer.desktop.in
thunar-thumbnailers-0.4.1/raw-thumbnailer/Makefile.am
thunar-thumbnailers-0.4.1/raw-thumbnailer/Makefile.in
thunar-thumbnailers-0.4.1/raw-thumbnailer/raw-thumbnailer
thunar-thumbnailers-0.4.1/INSTALL
thunar-thumbnailers-0.4.1/eps-thumbnailer/
thunar-thumbnailers-0.4.1/eps-thumbnailer/Makefile.am
thunar-thumbnailers-0.4.1/eps-thumbnailer/Makefile.in
thunar-thumbnailers-0.4.1/eps-thumbnailer/eps-thumbnailer.desktop.in
thunar-thumbnailers-0.4.1/eps-thumbnailer/eps-thumbnailer
thunar-thumbnailers-0.4.1/ChangeLog
thunar-thumbnailers-0.4.1/COPYING
thunar-thumbnailers-0.4.1/ffmpeg-thumbnailer/
thunar-thumbnailers-0.4.1/ffmpeg-thumbnailer/Makefile.am
thunar-thumbnailers-0.4.1/ffmpeg-thumbnailer/Makefile.in
thunar-thumbnailers-0.4.1/ffmpeg-thumbnailer/ffmpeg-thumbnailer.desktop.in
thunar-thumbnailers-0.4.1/ffmpeg-thumbnailer/ffmpeg-thumbnailer
thunar-thumbnailers-0.4.1/psd-thumbnailer/
thunar-thumbnailers-0.4.1/psd-thumbnailer/Makefile.am
thunar-thumbnailers-0.4.1/psd-thumbnailer/Makefile.in
thunar-thumbnailers-0.4.1/psd-thumbnailer/psd-thumbnailer.desktop.in
thunar-thumbnailers-0.4.1/psd-thumbnailer/psd-thumbnailer
thunar-thumbnailers-0.4.1/svgz-thumbnailer/
thunar-thumbnailers-0.4.1/svgz-thumbnailer/Makefile.am
thunar-thumbnailers-0.4.1/svgz-thumbnailer/Makefile.in
thunar-thumbnailers-0.4.1/svgz-thumbnailer/svgz-thumbnailer.desktop.in
thunar-thumbnailers-0.4.1/svgz-thumbnailer/svgz-thumbnailer
checking build system type... x86_64-slackware-linux-gnu
checking host system type... x86_64-slackware-linux-gnu
checking target system type... x86_64-slackware-linux-gnu
checking for a BSD-compatible install... /usr/bin/ginstall -c
checking whether build environment is sane... yes
checking for a thread-safe mkdir -p... /usr/bin/mkdir -p
checking for gawk... gawk
checking whether make sets $(MAKE)... yes
checking how to create a ustar tar archive... gnutar
checking whether to enable maintainer-specific portions of Makefiles... no
checking for a BSD-compatible install... /usr/bin/ginstall -c
checking for convert... /usr/bin/convert
checking for unzip... /usr/bin/unzip
checking for latex... /usr/share/texmf/bin/latex
configure: creating ./config.status
config.status: creating Makefile
config.status: creating eps-thumbnailer/Makefile
config.status: creating tex-thumbnailer/Makefile
config.status: creating ps-thumbnailer/Makefile
config.status: creating raw-thumbnailer/Makefile
config.status: creating fig-thumbnailer/Makefile
config.status: creating agr-thumbnailer/Makefile
config.status: creating ffmpeg-thumbnailer/Makefile
config.status: creating ogg-thumbnailer/Makefile
config.status: creating svgz-thumbnailer/Makefile
config.status: creating pdf-thumbnailer/Makefile
config.status: creating dvi-thumbnailer/Makefile
config.status: creating odf-thumbnailer/Makefile
config.status: creating xcf-thumbnailer/Makefile
config.status: creating psd-thumbnailer/Makefile
config.status: creating mime/Makefile
config.status: creating config.h
./thunar-thumbnailers.SlackBuild: line 84: --enable-ffmpeg: command not foundand yes, I have ffmpeg installed, as well as ffmpegthumbnailer.