[facebook] add support

docs/configuration.rst

@@ -2018,6 +2018,30 @@ Description
     * ``"hitomi"``:  Download the corresponding gallery from ``hitomi.la``
 
 
+extractor.facebook.author-followups
+-------------------------
+Type
+    ``bool``
+Default
+    ``false``
+description
+    Extract comments that include photo attachments made by the author of the post.
+
+
+extractor.facebook.videos
+-----------------------
+Type
+    * ``bool``
+    * ``string``
+Default
+    ``true``
+Description
+    Control video download behavior.
+
+    * ``true``: Extract and download video & audio separately.
+    * ``"ytdl"``: Let |ytdl| handle video extraction and download, and merge video & audio streams.
+
+
 extractor.fanbox.embeds
 -----------------------
 Type

docs/supportedsites.md

@@ -211,6 +211,12 @@ Consider all listed sites to potentially be NSFW.
     <td>Favorites, Galleries, Search Results</td>
     <td>Supported</td>
 </tr>
+<tr>
+    <td>Facebook</td>
+    <td>https://www.facebook.com/</td>
+    <td>Photos, Profiles, Sets, Videos</td>
+    <td><a href="https://github.com/mikf/gallery-dl#cookies">Cookies</a></td>
+</tr>
 <tr>
     <td>Fanleaks</td>
     <td>https://fanleaks.club/</td>

gallery_dl/extractor/__init__.py

@@ -44,6 +44,7 @@
     "e621",
     "erome",
     "exhentai",
+    "facebook",
     "fanbox",
     "fanleaks",
     "fantia",