diff --git a/README.md b/README.md
index 0c0cdc0ec770f7f2789d9894ac5e2725d2f4fe3c..2c855bffc146295d1e78d3a0392f193ada7f27e4 100644
--- a/README.md
+++ b/README.md
@@ -5,6 +5,7 @@
 This project is to make planar speakers by plotting fine magnet wire on a membrane, instead of the usual voice-coil and cone construction.  The resulting speakers will be low profile, low mass, and (hopefully) high performance.  It's my hope that by reducing the relevant design degrees of freedom (the path of the coils, the arrangement of permanent magnets) we can design the geometry and actuation of sound systems as a whole, rather than as assemblages of individually optimized components.
 
 <img src= "img/speaker-microscope.jpg" height=400px>
+<img src= "img/plotting.mp4" height=400px>
 
 
 
@@ -41,6 +42,8 @@ Stereo:
 <img src="img/output.mp4" height=400px>
 
 
+## Refinements to first prototypes
+
 I did some more prototyping on this design, using milled 1/16" cotton-phenolic, instead of laser-cut 1/8" plywood.  I also cured the membrane onto a thin sheet of carbon with a 0,+60,-60 layup.  I also switched to 1/8" (D) x 1/16" (H) magnets, instead of 1/8" (D) x 1/8" (H), because the simulations predicted the force output would be similar.
 
 <img src= "img/phenolic-magnets.jpg" height=300px>