--- a/dom/media/mediasource/TrackBuffersManager.cpp
+++ b/dom/media/mediasource/TrackBuffersManager.cpp
@@ -1655,21 +1655,24 @@ TrackBuffersManager::InsertFrames(TrackB
   // 16. Add the coded frame with the presentation timestamp, decode timestamp, and frame duration to the track buffer.
   if (!CheckNextInsertionIndex(aTrackData,
                                TimeUnit::FromMicroseconds(aSamples[0]->mTime))) {
     RejectProcessing(NS_ERROR_FAILURE, __func__);
     return;
   }
 
   // Adjust our demuxing index if necessary.
-  if (trackBuffer.mNextGetSampleIndex.isSome() &&
-      (trackBuffer.mNextInsertionIndex.ref() < trackBuffer.mNextGetSampleIndex.ref() ||
-       (trackBuffer.mNextInsertionIndex.ref() == trackBuffer.mNextGetSampleIndex.ref() &&
-        aIntervals.GetEnd() < trackBuffer.mNextSampleTime))) {
-    trackBuffer.mNextGetSampleIndex.ref() += aSamples.Length();
+  if (trackBuffer.mNextGetSampleIndex.isSome()) {
+    if (trackBuffer.mNextInsertionIndex.ref() == trackBuffer.mNextGetSampleIndex.ref() &&
+        aIntervals.GetEnd() >= trackBuffer.mNextSampleTime) {
+      MSE_DEBUG("Next sample to be played got overwritten");
+      trackBuffer.mNextGetSampleIndex.reset();
+    } else if (trackBuffer.mNextInsertionIndex.ref() <= trackBuffer.mNextGetSampleIndex.ref()) {
+      trackBuffer.mNextGetSampleIndex.ref() += aSamples.Length();
+    }
   }
 
   TrackBuffer& data = trackBuffer.mBuffers.LastElement();
   data.InsertElementsAt(trackBuffer.mNextInsertionIndex.ref(), aSamples);
   trackBuffer.mNextInsertionIndex.ref() += aSamples.Length();
 
   // Update our buffered range with new sample interval.
   // We allow a fuzz factor in our interval of half a frame length,

--- a/dom/media/mediasource/TrackBuffersManager.h
+++ b/dom/media/mediasource/TrackBuffersManager.h
@@ -258,16 +258,18 @@ private:
     // Byte size of all samples contained in this track buffer.
     uint32_t mSizeBuffer;
     // TrackInfo of the first metadata received.
     nsRefPtr<SharedTrackInfo> mInfo;
     // TrackInfo of the last metadata parsed (updated with each init segment.
     nsRefPtr<SharedTrackInfo> mLastInfo;
 
     // If set, position of the next sample to be retrieved by GetSample().
+    // If the position is equal to the TrackBuffer's length, it indicates that
+    // we've reached EOS.
     Maybe<uint32_t> mNextGetSampleIndex;
     // Approximation of the next sample's decode timestamp.
     media::TimeUnit mNextSampleTimecode;
     // Approximation of the next sample's presentation timestamp.
     media::TimeUnit mNextSampleTime;
 
     void ResetAppendState()
     {