embed: Use youtube-nocookie.com

YouTube supports embedding videos with "privacy enhanced mode" [1].
This is done by using https://www.youtube-nocookie.com/embed instead of
https://www.youtube.com/embed.

Override wagtails oembed finder to fixup the url we've got from YouTubes
oEmbed API.

We still load external content and need to trust Google, but it could be
verified, that no tracking cookies are sent around. This is even true,
when the video is actually played.

[1]: https://support.google.com/youtube/answer/171780

diff --git a/config/settings/base.py b/config/settings/base.py
index cd2857f..328b3c4 100644
--- a/config/settings/base.py
+++ b/config/settings/base.py
@@ -254,3 +254,5 @@ DOCS_ROOT = os.path.join(ROOT_DIR, 'docs/_build/html')
 WAGTAILAPI_LIMIT_MAX = 50

 DATA_UPLOAD_MAX_NUMBER_FIELDS=None
+
+WAGTAILEMBEDS_FINDERS = [ {  'class': 'mpicms.base.oembed' } ]
diff --git a/mpicms/base/oembed.py b/mpicms/base/oembed.py
new file mode 100644
index 0000000..db82820
--- /dev/null
+++ b/mpicms/base/oembed.py
@@ -0,0 +1,9 @@
+import wagtail.embeds.finders.oembed
+
+class OEmbedFinder(wagtail.embeds.finders.oembed.embed_finder_class):
+    def find_embed(self, url, max_width=None):
+        d = super().find_embed(url, max_width);
+        d['html'] = d['html'].replace('https://www.youtube.com/embed/', 'https://www.youtube-nocookie.com/embed/', 1)
+        return d
+
+embed_finder_class = OEmbedFinder

config/settings/base.py

@@ -254,3 +254,5 @@
 WAGTAILAPI_LIMIT_MAX = 50
 
 DATA_UPLOAD_MAX_NUMBER_FIELDS=None
+
+WAGTAILEMBEDS_FINDERS = [ {  'class': 'mpicms.base.oembed' } ]

mpicms/base/oembed.py

@@ -0,0 +1,9 @@
+import wagtail.embeds.finders.oembed
+
+class OEmbedFinder(wagtail.embeds.finders.oembed.embed_finder_class):
+    def find_embed(self, url, max_width=None):
+        d = super().find_embed(url, max_width);
+        d['html'] = d['html'].replace('https://www.youtube.com/embed/', 'https://www.youtube-nocookie.com/embed/', 1)
+        return d
+
+embed_finder_class = OEmbedFinder