diff --git a/src/invidious/routes/before_all.cr b/src/invidious/routes/before_all.cr
index 5695dee9..0cc04021 100644
--- a/src/invidious/routes/before_all.cr
+++ b/src/invidious/routes/before_all.cr
@@ -20,14 +20,6 @@ module Invidious::Routes::BeforeAll
     env.response.headers["X-XSS-Protection"] = "1; mode=block"
     env.response.headers["X-Content-Type-Options"] = "nosniff"
 
-    # Allow media resources to be loaded from google servers
-    # TODO: check if *.youtube.com can be removed
-    if CONFIG.disabled?("local") || !preferences.local
-      extra_media_csp = " https://*.googlevideo.com:443 https://*.youtube.com:443"
-    else
-      extra_media_csp = ""
-    end
-
     # Only allow the pages at /embed/* to be embedded
     if env.request.resource.starts_with?("/embed")
       frame_ancestors = "'self' file: http: https:"
@@ -45,7 +37,7 @@ module Invidious::Routes::BeforeAll
       "font-src 'self' data:",
       "connect-src 'self'",
       "manifest-src 'self'",
-      "media-src 'self' blob:" + extra_media_csp,
+      "media-src 'self' blob:",
       "child-src 'self' blob:",
       "frame-src 'self'",
       "frame-ancestors " + frame_ancestors,
@@ -110,6 +102,20 @@ module Invidious::Routes::BeforeAll
     preferences.locale = locale
     env.set "preferences", preferences
 
+    # Allow media resources to be loaded from google servers
+    # TODO: check if *.youtube.com can be removed
+    #
+    # `!preferences.local` has to be checked after setting and
+    # reading `preferences` from the "PREFS" cookie and
+    # saved user preferences from the database, otherwise
+    # the `extra_media_csp` variable will be always empty if
+    # `default_user_preferences.local` is set to true on the
+    # configuration file, causing preference “Proxy Videos”
+    # not to work.
+    if CONFIG.disabled?("local") || !preferences.local
+      env.response.headers["Content-Security-Policy"] = env.response.headers["Content-Security-Policy"].gsub("media-src", "media-src https://*.googlevideo.com:443 https://*.youtube.com:443")
+    end
+
     current_page = env.request.path
     if env.request.query
       query = HTTP::Params.parse(env.request.query.not_nil!)