This feature enables you to work with your content without losing the context of what you are doing.
Document Types are in different sections than content but infinite editing enables you to make changes to them directly from the content you are editing.
In the example showcased above, prevalues are being added to a Data Type, without losing the context of the content that's being worked on. The example also shows how you can edit images, without being sent to the 'Media' section.
Infinite editing is a feature that comes out of the box with Umbraco 8. The feature can be customized, which enables you as a developer to improve the workflow for your editors.