Popular content in video sharing websites (e.g., YouTube) contains many duplicates. Most scholars define near-duplicate video clips (NDVC) as identical videos with variations on non-semantic features (e.g., image/audio quality), while a few others also include semantic features (different videos of similar content). However, it is unclear what exact features contribute to human perception of similar videos. In this paper, we present the results of a user study conducted with 217 users of video sharing websites. Findings confirm the relevance of both classes of features, but the exact role played by semantics on each instance of NDVC is still an open question. In most cases, participants had a preference for one video when compared to its NDVC and they were more tolerant to changes in the audio than in the video channel.