First, create a RubberDuck Video Gallery widget on Common Ninja.
On the widgets catalog, find the Video Gallery and enter the Editor.
When you're done creating the Video Gallery widget, click on the Save Changes button at the right top corner of the editor.
If you don't have an account on Common Ninja, you'll have to register first.
When you're ready to add the Video Gallery widget to your RubberDuck website, click the Add To Website button at the top bar of the Editor.
On the window that opens, click the Copy Icon to copy the widget embed code. In the next steps, you will paste this code into your RubberDuck [site_type].
Now, let's head to your RubberDuck website's editor.
In the RubberDuck editor, click on Add New Section, wherever you wish the Video Gallery will show.
Search and select the Script section type.
On the new Section you've added to your page, click the Edit icon.
Now, in the script window, simply paste the Video Gallery embed code you've copied before.
Click on the Continue button at the top of the Script window, to close it.