diff --git a/dom/media/mediasource/MediaSource.cpp b/dom/media/mediasource/MediaSource.cpp
index 79f380a3ad01..a3609e65e38c 100644
--- a/dom/media/mediasource/MediaSource.cpp
+++ b/dom/media/mediasource/MediaSource.cpp
@@ -88,6 +88,41 @@ static bool IsVP9Forced(DecoderDoctorDiagnostics* aDiagnostics) {
 
 namespace dom {
 
+static void RecordTypeForTelemetry(const nsAString& aType,
+                                   nsPIDOMWindowInner* aWindow) {
+  Maybe<MediaContainerType> containerType = MakeMediaContainerType(aType);
+  if (!containerType) {
+    return;
+  }
+
+  const MediaMIMEType& mimeType = containerType->Type();
+  if (mimeType == MEDIAMIMETYPE(VIDEO_WEBM)) {
+    AccumulateCategorical(
+        mozilla::Telemetry::LABELS_MSE_SOURCE_BUFFER_TYPE::VideoWebm);
+  } else if (mimeType == MEDIAMIMETYPE(AUDIO_WEBM)) {
+    AccumulateCategorical(
+        mozilla::Telemetry::LABELS_MSE_SOURCE_BUFFER_TYPE::AudioWebm);
+  } else if (mimeType == MEDIAMIMETYPE(VIDEO_MP4)) {
+    AccumulateCategorical(
+        mozilla::Telemetry::LABELS_MSE_SOURCE_BUFFER_TYPE::VideoMp4);
+  } else if (mimeType == MEDIAMIMETYPE(AUDIO_MP4)) {
+    AccumulateCategorical(
+        mozilla::Telemetry::LABELS_MSE_SOURCE_BUFFER_TYPE::AudioMp4);
+  } else if (mimeType == MEDIAMIMETYPE(VIDEO_MPEG_TS)) {
+    AccumulateCategorical(
+        mozilla::Telemetry::LABELS_MSE_SOURCE_BUFFER_TYPE::VideoMp2t);
+  } else if (mimeType == MEDIAMIMETYPE(AUDIO_MPEG_TS)) {
+    AccumulateCategorical(
+        mozilla::Telemetry::LABELS_MSE_SOURCE_BUFFER_TYPE::AudioMp2t);
+  } else if (mimeType == MEDIAMIMETYPE(AUDIO_MP3)) {
+    AccumulateCategorical(
+        mozilla::Telemetry::LABELS_MSE_SOURCE_BUFFER_TYPE::AudioMpeg);
+  } else if (mimeType == MEDIAMIMETYPE(AUDIO_AAC)) {
+    AccumulateCategorical(
+        mozilla::Telemetry::LABELS_MSE_SOURCE_BUFFER_TYPE::AudioAac);
+  }
+}
+
 /* static */
 void MediaSource::IsTypeSupported(const nsAString& aType,
                                   DecoderDoctorDiagnostics* aDiagnostics,
@@ -241,6 +276,7 @@ already_AddRefed<SourceBuffer> MediaSource::AddSourceBuffer(
   MOZ_ASSERT(NS_IsMainThread());
   DecoderDoctorDiagnostics diagnostics;
   IsTypeSupported(aType, &diagnostics, aRv);
+  RecordTypeForTelemetry(aType, GetOwner());
   bool supported = !aRv.Failed();
   diagnostics.StoreFormatDiagnostics(
       GetOwner() ? GetOwner()->GetExtantDoc() : nullptr, aType, supported,
@@ -394,6 +430,7 @@ bool MediaSource::IsTypeSupported(const GlobalObject& aOwner,
   bool supported = !rv.Failed();
   nsCOMPtr<nsPIDOMWindowInner> window =
       do_QueryInterface(aOwner.GetAsSupports());
+  RecordTypeForTelemetry(aType, window);
   diagnostics.StoreFormatDiagnostics(window ? window->GetExtantDoc() : nullptr,
                                      aType, supported, __func__);
   MOZ_LOG(GetMediaSourceAPILog(), mozilla::LogLevel::Debug,
diff --git a/netwerk/mime/nsMimeTypes.h b/netwerk/mime/nsMimeTypes.h
index 210e97a09446..6f9ad7f76563 100644
--- a/netwerk/mime/nsMimeTypes.h
+++ b/netwerk/mime/nsMimeTypes.h
@@ -90,6 +90,7 @@
 #define AUDIO_MIDI "audio/x-midi"
 #define AUDIO_MATROSKA "audio/x-matroska"
 #define AUDIO_AAC "audio/aac"
+#define AUDIO_MPEG_TS "audio/mp2t"
 
 #define BINARY_OCTET_STREAM "binary/octet-stream"
 
diff --git a/toolkit/components/telemetry/Histograms.json b/toolkit/components/telemetry/Histograms.json
index 8477b8810a18..1021507978a6 100644
--- a/toolkit/components/telemetry/Histograms.json
+++ b/toolkit/components/telemetry/Histograms.json
@@ -13291,6 +13291,17 @@
     "releaseChannelCollection": "opt-out",
     "description": "Count of use of audio/video codecs in HTMLMediaElements and WebAudio. Those with 'resource' prefix are approximate; report based on HTTP ContentType or sniffing. Those with 'webaudio' prefix are for WebAudio."
   },
+  "MSE_SOURCE_BUFFER_TYPE": {
+    "products": ["firefox", "geckoview_streaming"],
+    "record_in_processes": ["main", "content"],
+    "alert_emails": ["alwu@mozilla.com", "bryce@mozilla.com"],
+    "bug_numbers": [1699249],
+    "expires_in_version": "never",
+    "kind": "categorical",
+    "labels": ["VideoWebm", "AudioWebm", "VideoMp4", "AudioMp4", "VideoMp2t", "AudioMp2t", "AudioMpeg", "AudioAac"],
+    "releaseChannelCollection": "opt-out",
+    "description": "Count the actual or possible (because we don't support some of them for now) usage amount for each media mime type used in MSE. We collect this data in MediaSource's `AddSourceBuffer()` and `IsTypeSupported()`."
+  },
   "FX_SANITIZE_TOTAL": {
     "record_in_processes": ["main", "content"],
     "products": ["firefox", "fennec"],