operation.setOperator(Operator.SET);
VideoCallToActionOperation[] operations = new VideoCallToActionOperation[] {operation};
// Add video call to action.
VideoReturnValue result = videoService.mutateCallToAction(operations);
for (YouTubeVideo youTubeVideoResult : result.getValue()) {
System.out.printf("CallToAction overlay was added to video ID %s, "
+ "headline '%s'.%n",
youTubeVideoResult.getId(),
youTubeVideoResult.getCallToAction().getCreative().getHeadline());
}