diff --git a/content/media/MediaDecoderStateMachine.cpp b/content/media/MediaDecoderStateMachine.cpp
index 7e7f38e8c20..457afc2f156 100644
--- a/content/media/MediaDecoderStateMachine.cpp
+++ b/content/media/MediaDecoderStateMachine.cpp
@@ -506,7 +506,8 @@ void MediaDecoderStateMachine::SendStreamAudio(AudioData* aAudio,
                                                DecodedStreamData* aStream,
                                                AudioSegment* aOutput)
 {
-  NS_ASSERTION(OnDecodeThread(), "Should be on decode thread.");
+  NS_ASSERTION(OnDecodeThread() ||
+               OnStateMachineThread(), "Should be on decode thread or state machine thread");
   mDecoder->GetReentrantMonitor().AssertCurrentThreadIn();
 
   if (aAudio->mTime <= aStream->mLastAudioPacketTime) {
@@ -1210,7 +1211,7 @@ uint32_t MediaDecoderStateMachine::PlaySilence(uint32_t aFrames,
 }
 
 uint32_t MediaDecoderStateMachine::PlayFromAudioQueue(uint64_t aFrameOffset,
-                                                          uint32_t aChannels)
+                                                      uint32_t aChannels)
 {
   NS_ASSERTION(OnAudioThread(), "Only call on audio thread.");
   NS_ASSERTION(!mAudioStream->IsPaused(), "Don't play when paused");
@@ -1218,7 +1219,6 @@ uint32_t MediaDecoderStateMachine::PlayFromAudioQueue(uint64_t aFrameOffset,
   {
     ReentrantMonitorAutoEnter mon(mDecoder->GetReentrantMonitor());
     NS_WARN_IF_FALSE(IsPlaying(), "Should be playing");
-    NS_ASSERTION(!mAudioCaptured, "Audio cannot be captured here!");
     // Awaken the decode loop if it's waiting for space to free up in the
     // audio queue.
     mDecoder->GetReentrantMonitor().NotifyAll();
diff --git a/content/media/test/Makefile.in b/content/media/test/Makefile.in
index d309c14d261..d19837cd6a7 100644
--- a/content/media/test/Makefile.in
+++ b/content/media/test/Makefile.in
@@ -133,6 +133,7 @@ MOCHITEST_FILES = \
 		test_media_sniffer.html \
 		contentType.sjs \
 		test_streams_srcObject.html \
+		test_streams_gc.html \
 		$(filter disabled-for-intermittent-failures--bug-608634, test_error_in_video_document.html) \
 		$(NULL)
 
diff --git a/content/media/test/test_streams_gc.html b/content/media/test/test_streams_gc.html
new file mode 100644
index 00000000000..545b0c19286
--- /dev/null
+++ b/content/media/test/test_streams_gc.html
@@ -0,0 +1,45 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test garbage collection of captured stream (bug 806754)</title>
+  <script type="text/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+  <script type="text/javascript" src="manifest.js"></script>
+</head>
+<body onload="doTest()">
+<audio id="a"></audio>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+SimpleTest.waitForExplicitFinish();
+
+var a = document.getElementById('a');
+a.src = getPlayableAudio(gSmallTests).name;
+
+function forceGC() {
+  SpecialPowers.gc();
+  SpecialPowers.forceGC();
+  SpecialPowers.forceCC();
+}
+
+function doTest() {
+  a.mozCaptureStreamUntilEnded();
+
+  a.addEventListener("seeked", function() {
+    a.play();
+
+    a.addEventListener("play", function() {
+      a.addEventListener("ended", function() {
+        ok(true, "GC completed OK");
+        SimpleTest.finish();
+      }, false);
+    }, false);
+  }, false);
+
+  a.currentTime = a.duration;
+  
+  setTimeout(forceGC, 0);
+}
+</script>
+</pre>
+</body>
+</html>
