What you see in the video, is the standard accordion widget, styled with colours and "filled with a standard menu. Additionally the title bar is "filled" with an icon, which changes state-wise.
In the video Danielle de Beaumont drags directly this widget accordeon of the Library, which opens with a burger displayed.
I do not have the same rendering if I do the same manipulation.
No. Look again!
She literally says:
"Now to save time, I’ve already designed this accordion widget. I pulled it out of the widget library and selected the accordion here and I designed some attributes, and as I paste this back to the canvas you can see … "
Also, you might have noticed, that Dani closes the widget panel, before the accordion appears on the canvas widget panel.
You see, you have to configure the accordion by yourself. Just try it, it’s very easy!
By the way: Here you find the finished demo site: http://www.kickapigeon.com/index.html
Thank you for this clarification, but the confusion also comes from the translation between what is said by Dani and what is written in the French subtitling.
I will see the demo.