diff --git a/youtube_dl/YoutubeDL.py b/youtube_dl/YoutubeDL.py
index 15eca7e56..8b4a2ff5f 100755
--- a/youtube_dl/YoutubeDL.py
+++ b/youtube_dl/YoutubeDL.py
@@ -1031,6 +1031,9 @@ class YoutubeDL(object):
                 for j, part in enumerate(format['parts']):
                     if 'url' not in part:
                         raise ExtractorError('Missing "url" key in result (index %d, part %d)' % (i, j))
+                    full_format_info = info_dict.copy()
+                    full_format_info.update(part)
+                    part['http_headers'] = self._calc_headers(full_format_info)
             else:
                 if 'url' not in format:
                     raise ExtractorError('Missing "url" key in result (index %d)' % i)
@@ -1046,11 +1049,12 @@ class YoutubeDL(object):
             # Automatically determine file extension if missing
             if 'ext' not in format:
                 format['ext'] = determine_ext(format['url']).lower()
-            # Add HTTP headers, so that external programs can use them from the
-            # json output
-            full_format_info = info_dict.copy()
-            full_format_info.update(format)
-            format['http_headers'] = self._calc_headers(full_format_info)
+            if 'parts' not in format:
+                # Add HTTP headers, so that external programs can use them from the
+                # json output
+                full_format_info = info_dict.copy()
+                full_format_info.update(format)
+                format['http_headers'] = self._calc_headers(full_format_info)
 
         format_limit = self.params.get('format_limit', None)
         if format_limit:
diff --git a/youtube_dl/__init__.py b/youtube_dl/__init__.py
index 09de067e9..5182dac15 100644
--- a/youtube_dl/__init__.py
+++ b/youtube_dl/__init__.py
@@ -234,6 +234,8 @@ def _real_main(argv=None):
         if not opts.addmetadata:
             postprocessors.append({'key': 'FFmpegAudioFix'})
         postprocessors.append({'key': 'AtomicParsley'})
+    if opts.joinparts:
+        postprocessors.append({'key': 'FFmpegJoinVideos'})
     # Please keep ExecAfterDownload towards the bottom as it allows the user to modify the final file in any way.
     # So if the user is able to remove the file before your postprocessor runs it might cause a few problems.
     if opts.exec_cmd:
diff --git a/youtube_dl/postprocessor/ffmpeg.py b/youtube_dl/postprocessor/ffmpeg.py
index e07f7cc97..0087786ff 100644
--- a/youtube_dl/postprocessor/ffmpeg.py
+++ b/youtube_dl/postprocessor/ffmpeg.py
@@ -134,7 +134,7 @@ class FFmpegPostProcessor(PostProcessor):
         files_cmd = []
         for path in input_paths:
             files_cmd.extend([encodeArgument('-i'), encodeFilename(path, True)])
-        cmd = ([encodeFilename(self._executable, True), encodeArgument('-y')] +
+        cmd = ([encodeFilename(self.executable, True), encodeArgument('-y')] +
                [encodeArgument(o) for o in input_opts] + files_cmd + [encodeArgument(o) for o in opts] +
                [encodeFilename(self._ffmpeg_filename_argument(out_path), True)])