[reddit] use 'dash_url' for videos (#3258) (#3306)

* use fallback_url for reddit_video to fix issue 3258

* changed to dash_url to include audio

* update

- use [] instead of .get
- catch TypeErrors in case one of the elements is not a dict

Co-authored-by: InterruptSpeed <steven@docherty.ca>
Co-authored-by: Mike Fährmann <mike_faehrmann@web.de>

gallery_dl/extractor/reddit.py

@@ -69,6 +69,11 @@ class RedditExtractor(Extractor):
                                 submission["_ytdl_extra"] = {
                                     "title": submission["title"],
                                 }
+                                try:
+                                    url = (submission["secure_media"]
+                                           ["reddit_video"]["dash_url"])
+                                except (KeyError, TypeError):
+                                    pass
                             yield Message.Url, "ytdl:" + url, submission
 
                     elif not submission["is_self"]: