Merge pull request #13148 from meeseeksmachine/auto-backport-of-pr-13147-on-7.x

Backport PR  #13147 on branch 7.x (Reword the YouTubeVideo autoplay WN)

docs/source/whatsnew/pr/enable-to-add-extra-attrs-to-iframe.rst

@@ -1,13 +1,15 b''
-Enable to add extra attributes to iframe
-========================================
+``YouTubeVideo`` autoplay and the ability to add extra attributes to ``IFrame``
+===============================================================================
 
-You can add any extra attributes to the ``<iframe>`` tag
-since the argument ``extras`` has been added to the ``IFrame`` class.
-for example::
+You can add any extra attributes to the ``<iframe>`` tag using the new
+``extras`` argument in the ``IFrame`` class. For example::
 
     In [1]: from IPython.display import IFrame
 
-    In [2]: print(IFrame(src="src", width=300, height=300, extras=["hello", "world"])._repr_html_())
+    In [2]: IFrame(src="src", width=300, height=300, extras=['loading="eager"'])
+
+The above cells will result in the following HTML code being displayed in a
+notebook::
 
             <iframe
                 width="300"
@@ -15,23 +17,22 b' for example::'
                 src="src"
                 frameborder="0"
                 allowfullscreen
-                hello world
+        loading="eager"
             ></iframe>
 
-Using it, you can autoplay ``YouTubeVideo`` by adding ``'allow="autoplay"'``,
-even in browsers that disable it by default, such as Google Chrome.
-And, you can write it more briefly by using the argument ``allow_autoplay``.
+Related to the above, the ``YouTubeVideo`` class now takes an
+``allow_autoplay`` flag, which sets up the iframe of the embedded YouTube video
+such that it allows autoplay.
+
+.. note::
+    Whether this works depends on the autoplay policy of the browser rendering
+    the HTML allowing it. It also could get blocked by some browser extensions.
+
+Try it out!
 ::
 
     In [1]: from IPython.display import YouTubeVideo
 
-    In [2]: print(YouTubeVideo("video-id", allow_autoplay=True)._repr_html_())
+    In [2]: YouTubeVideo("dQw4w9WgXcQ", allow_autoplay=True)
 
-            <iframe
-                width="400"
-                height="300"
-                src="https://www.youtube.com/embed/video-id?autoplay=1"
-                frameborder="0"
-                allowfullscreen
-                allow="autoplay"
-            ></iframe>
+🙃