diff --git a/getusermedia.html b/getusermedia.html
index f114b12e..3a45aeb2 100644
--- a/getusermedia.html
+++ b/getusermedia.html
@@ -545,7 +545,10 @@ <h2>MediaStream</h2>
     <section>
       <h2>MediaStreamTrack</h2>
       <p>A <code><a>MediaStreamTrack</a></code> object represents a media
-      source in the User Agent. Several <code><a>MediaStreamTrack</a></code>
+      source in the User Agent. An example source is a device connected to the
+      User Agent. Other specifications may define sources for <code>
+      <a>MediaStreamTrack</a></code> that override the behavior specified here.
+      Several <code><a>MediaStreamTrack</a></code>
       objects can represent the same media source, e.g., when the user chooses
       the same camera in the UI shown by two consecutive calls to
       <code><a>getUserMedia()</a></code> .</p>
@@ -881,15 +884,12 @@ <h3>Interface Definition</h3>
                 <p>Let <var>track</var> be the current
                 <code><a>MediaStreamTrack</a></code> object.</p>
               </li>
-              <li>
-                <p>If <var>track</var> is sourced by a non-local source, then
-                abort these steps.</p>
-              </li>
               <li>
                 <p>Notify <var>track</var>'s source that <var>track</var> is
-                <a href="#track-ended">ended</a> so that the source may be
-                <a href="#source-stopped">stopped</a>, unless other
-                <code><a>MediaStreamTrack</a></code> objects depend on it.</p>
+                <a href="#track-ended">ended</a>.</p>
+                <p>A source that is notified of a track ending will be <a href=
+                "#source-stopped">stopped</a>, unless other <code>
+                <a>MediaStreamTrack</a></code> objects depend on it.</p>
               </li>
               <li>
                 <p>Set <var>track's</var> <code><a href=