It has tons of requirements.
It lists these requirements:
PyCHM >= 0.8.4
pygtk2
pygtk2-libglade
gnome-python2
gnome-python2-gtkhtml2
gnome-python2-gconf
gnome-python2-bonobo
gnome-python2-canvas
Also it obviously depends on python.
pygtk2-libglade will depend on libglade and libxml2.
gnome-python2 depends on libbonobo and libbonoboui and libgconf2 and libgnome2 and libgnomecanvas2 and libgnomeui2 and libgnomevfs2 and liborbit2 and more.
libgnome2 depends on gvfs and libgnome2-common, which in turn depends on librsvg2-common, which in turn depends on librsvg2, which in turn depends on libcroco3 and libgsf-1.
libgnomecanvas2 depends on libart-2.
gnome-python2-gtkhtml2 depends on libgtkhtml2.
All those packages you may not want and may not find for your distro, just to view the help file? People are already complaining that installing PB for Linux is hard.