Added more info

Demo/sgi/sv/README

 Demo programs for the SGI Video library for the Indigo (IRIX 4.0.5).
+
 These are more-or-less literal translations of the C programs from the
-Indigo Video Programming Guide, by Sjoerd Mullender, with minor
-changes by Guido.
+Indigo Video Programming Guide, by Sjoerd Mullender, with some changes
+by Guido.
+
+Note that none of the example programs save any data to a file,
+although this would be easy to do (e.g. individual grabbed frames
+could be written as SGI image files using the imgfile module).
+
+We have written a Python program to record live video to file (within
+the limits of the Indigo video board), and a suite of programs to
+manipulate and display such files.  At the moment we don't distribute
+these programs, since the file format is, eh..., weird, to say the
+least.  However, if you are really interested we can mail you the
+source.
+
+Also note that we haven't tried using video *output* yet.
 
 simpleinput.py		Live video in a resizable window
 rgbgrab.py		Grab still frames
-contcapt.py		Continuous capturing (to a window)
+contcapt.py		Continuous capturing
 burstcapt.py		Burst capturing