Fourteen-month-olds selectively imitated a sub-efficient means (illuminating a lightbox by a head-touch) when this was modeled by linguistic ingroup members in video-demonstrations. A follow-up study with slightly older infants, however, could replicate this effect only in a video-demonstration context. Hence it still remains unclear whether infants' apparent tendency to be selective in learning opaque manners of novel skills from linguistic ingroup members is, indeed, a characteristic constraining property of cultural knowledge transmission that can be reliably manifested in live demonstration contexts that are more representative of naturalistic learning environments. To answer this question, we aimed to replicate the original study using live demonstration with a group of older infants (N = 48; 28 females). We found that eighteen-month-olds imitated the opaque manner of sub-efficient means action as a function of whether the demonstrator was a speaker of their own language. In a no-demonstration control group, infants relied on the self-discovered efficient means (hand-action), just like infants observing the foreign speaker. These findings suggest that selectivity in learning sub-efficient opaque actions from linguistic ingroups has evolved to support transmission of culture-specific manner of action practices shared within social groups.