+        self._write_thumbnails(info_dict, filename)
+
+        if not self.params.get('skip_download', False):
+            try:
+                def dl(name, info):
+                    fd = get_suitable_downloader(info, self.params)(self, self.params)
+                    for ph in self._progress_hooks:
+                        fd.add_progress_hook(ph)
+                    if self.params.get('verbose'):
+                        self.to_stdout('[debug] Invoking downloader on %r' % info.get('url'))
+                    return fd.download(name, info)
+
+                if info_dict.get('requested_formats') is not None:
+                    downloaded = []
+                    success = True
+                    merger = FFmpegMergerPP(self)
+                    if not merger.available:
+                        postprocessors = []
+                        self.report_warning('You have requested multiple '
+                                            'formats but ffmpeg or avconv are not installed.'
+                                            ' The formats won\'t be merged')
+                    else:
+                        postprocessors = [merger]
+
+                    def compatible_formats(formats):
+                        video, audio = formats
+                        # Check extension
+                        video_ext, audio_ext = audio.get('ext'), video.get('ext')
+                        if video_ext and audio_ext:
+                            COMPATIBLE_EXTS = (
+                                ('mp3', 'mp4', 'm4a', 'm4p', 'm4b', 'm4r', 'm4v'),
+                                ('webm')
+                            )
+                            for exts in COMPATIBLE_EXTS:
+                                if video_ext in exts and audio_ext in exts:
+                                    return True
+                        # TODO: Check acodec/vcodec
+                        return False
+
+                    filename_real_ext = os.path.splitext(filename)[1][1:]
+                    filename_wo_ext = (
+                        os.path.splitext(filename)[0]
+                        if filename_real_ext == info_dict['ext']
+                        else filename)
+                    requested_formats = info_dict['requested_formats']
+                    if self.params.get('merge_output_format') is None and not compatible_formats(requested_formats):
+                        info_dict['ext'] = 'mkv'
+                        self.report_warning('You have requested formats incompatible for merge. '
+                                            'The formats will be merged into mkv')
+                    # Ensure filename always has a correct extension for successful merge
+                    filename = '%s.%s' % (filename_wo_ext, info_dict['ext'])
+                    if os.path.exists(encodeFilename(filename)):
+                        self.to_screen(
+                            '[download] %s has already been downloaded and '
+                            'merged' % filename)
+                    else:
+                        for f in requested_formats:
+                            new_info = dict(info_dict)
+                            new_info.update(f)
+                            fname = self.prepare_filename(new_info)
+                            fname = prepend_extension(fname, 'f%s' % f['format_id'], new_info['ext'])
+                            downloaded.append(fname)
+                            partial_success = dl(fname, new_info)
+                            success = success and partial_success
+                        info_dict['__postprocessors'] = postprocessors
+                        info_dict['__files_to_merge'] = downloaded
+                else:
+                    # Just a single file
+                    success = dl(filename, info_dict)
+            except (compat_urllib_error.URLError, compat_http_client.HTTPException, socket.error) as err:
+                self.report_error('unable to download video data: %s' % str(err))
+                return
+            except (OSError, IOError) as err:
+                raise UnavailableVideoError(err)
+            except (ContentTooShortError, ) as err:
+                self.report_error('content too short (expected %s bytes and served %s)' % (err.expected, err.downloaded))
+                return
+