Get smtube from svn, it works
Code:
svn co https://subversion.assembla.com/svn/smplayer/smtube/trunk/ smtube
cd smtube
./get_svn_revision.sh
make
You may want to change the prefix in the Makefile
before You "make install DESTDIR=/tmp/smtube"
then from the content of "/tmp/smtube"
You can build a slackware package with makepkg
Enjoy