A performance marketer needs an always-on metric to show YouTube's impact on search without an experiment setup. What should they use?

Attributed Branded Searches is the correct answer because it directly measures an increase in searches for a brand's terms on Google after exposure to YouTube ads, without requiring a formal experiment. This metric is always-on and reflects the direct impact of video advertising on search interest. Search Lift and Brand Lift are both experimental methodologies that require a control group and are not "always-on" metrics. Search Lift specifically measures incremental search volume due to ads, while Brand Lift measures changes in brand perception metrics like recall or consideration. GRP (Gross Rating Point) reporting is a traditional media planning metric for reach and frequency, not a direct measure of YouTube's impact on search behavior.