Clarifying use of codecs & metadata when making ranged requests

source

@@ -33017,11 +33017,15 @@ interface <dfn>HTMLMediaElement</dfn> : <span>HTMLElement</span> {
 
         <p>The user agent may go on to use whatever means necessary to fetch the resource (within
         the constraints put forward by this and other specifications); for example, reconnecting to
-        the server in the face of network errors, using the <span
-        data-x="concept-media-ranged-fetch-steps">ranged fetch steps</span> to
-        perform HTTP range retrieval requests for a given start and end range, or switching to a
-        streaming protocol. The user agent must consider a resource erroneous only if it has given
-        up trying to fetch it.</p>
+        the server in the face of network errors, or switching to a streaming protocol. The user
+        agent must consider a resource erroneous only if it has given up trying to fetch it.</p>
+
+        <p>The user agent may use the <span data-x="concept-media-ranged-fetch-steps">ranged fetch
+        steps</span> to perform HTTP range retrieval requests for a given start and (optional) end
+        range. Through its knowledge of container formats, the user agent may issue a ranged request
+        to gather metadata it knows to be at the end of the resource. Or, if the media is seeked,
+        the browser may use metadata to convert a temporal range to a byte range and make a ranged
+        request.</p>
 
         <p>To determine the format of the <span>media resource</span>, the user agent must use the
         <span data-x="Content-Type sniffing: video">rules for sniffing audio and video specifically</span>.</p>