GNU Make is necessary on *BSD.

Originally committed as revision 4937 to svn://svn.ffmpeg.org/ffmpeg/trunk

doc/ffmpeg-doc.texi

@@ -876,6 +876,9 @@ features only found in GCC 3.2.
 
 @section BSD
 
+BSD make will not build FFmpeg, you need to install and use GNU Make
+(@file{gmake}).
+
 @section Windows
 
 @subsection Native Windows compilation