Adds playback bar to story viewer

ts/util/timestamp.ts

@@ -103,7 +103,8 @@ export function formatDateTimeLong(
 export function formatTime(
   i18n: LocalizerType,
   rawTimestamp: RawTimestamp,
-  now: RawTimestamp
+  now: RawTimestamp,
+  isRelativeTime?: boolean
 ): string {
   const timestamp = rawTimestamp.valueOf();
   const diff = now.valueOf() - timestamp;
@@ -116,6 +117,10 @@ export function formatTime(
     return i18n('minutesAgo', [Math.floor(diff / MINUTE).toString()]);
   }
 
+  if (isRelativeTime) {
+    return i18n('hoursAgo', [Math.floor(diff / HOUR).toString()]);
+  }
+
   return new Date(timestamp).toLocaleTimeString([], {
     hour: 'numeric',
     minute: '2-digit',