Add <video> element fallback case for MediaStreamVideoTrackSource, adding Firefox support

dev/live.html

@@ -19,7 +19,7 @@
     button.addEventListener('click', async () => {
         const stream = await navigator.mediaDevices.getDisplayMedia({ video: true, audio: false });
         const videoTrack = stream.getVideoTracks()[0];
-        const audioTrack = null;//stream.getAudioTracks()[0];
+        const audioTrack = stream.getAudioTracks()[0];
 
         const output = new Mediabunny.Output({
             target: new Mediabunny.BufferTarget(),
@@ -29,7 +29,7 @@
 		let audioSource = null;
         if (videoTrack) {
             videoSource = new Mediabunny.MediaStreamVideoTrackSource(videoTrack, {
-                codec: 'avc',
+                codec: 'vp9',
                 bitrate: Mediabunny.QUALITY_MEDIUM,
 				sizeChangeBehavior: 'passThrough',
             });
@@ -40,13 +40,13 @@
         }
         if (audioTrack) {
             audioSource = new Mediabunny.MediaStreamAudioTrackSource(audioTrack, {
-                codec: 'mp3',
+                codec: 'opus',
                 bitrate: Mediabunny.QUALITY_MEDIUM
             });
 
             audioSource.errorPromise.catch((d) => console.log("Hello!!???", d));
 
-            //output.addAudioTrack(audioSource);
+            output.addAudioTrack(audioSource);
         }
 
         await output.start();