MDL-63453 media_videojs: Upgrade Video.JS to 7.6.5.

Upgrade videojs media player to version 7.6.5 as well
as a general update this adds MPEG-DASH and HLS playlist
support to the Video.JS media player.

lib/classes/useragent.php

@@ -1165,4 +1165,39 @@ class core_useragent {
 
         return true;
     }
+
+    /**
+     * Checks if current browser supports the HLS and MPEG-DASH video
+     * streaming formats. Most browsers get this from Media Source Extensions.
+     * Safari on iOS, doesn't support MPEG-DASH at all.
+     *
+     * Note, the check here is not 100% accurate!
+     *
+     * Also we assume that users of Firefox/Chrome/Safari do not use the ancient versions of browsers.
+     *
+     * We check the exact version for IE/Edge though. We know that there are still users of very old
+     * versions that are afraid to upgrade or have slow IT department.
+     *
+     * Resources:
+     * https://developer.mozilla.org/en-US/docs/Web/API/Media_Source_Extensions_API
+     * https://caniuse.com/#search=mpeg-dash
+     * https://caniuse.com/#search=hls
+     *
+     * @return bool
+     */
+    public static function supports_media_source_extensions(string $extension) : bool {
+        // Not supported in IE below 11.0.
+        if (self::is_ie() && !self::check_ie_version('11.0')) {
+            return false;
+        }
+
+        if ($extension == '.mpd') {
+            // Not supported is iOS on Safari.
+            if (self::is_safari_ios()) {
+                return false;
+            }
+        }
+
+        return true;
+    }
 }