The feature which the person was talking about is called search suggestions and, indeed, the searches get routed through the selected search provider. There is

The feature which the person was talking about is called search suggestions and, indeed, the searches get routed through the selected search provider. There is a related feature, Safari Suggestions, which seems to use the system's Spotlight search service to provide other suggestions. For people's information, these can be turned off in Safari preferences -> Search.