Attaching an ad banner on a clip in a video-sharing website such as YouTube has become common although eye-tracking studies have concluded that this fails to secure visitors’ attention. To date, there have been no studies verifying whether ad banners on a video clip can ensure eye fixation from viewers. Through eye-tracking, this study investigates whether YouTube visitors fixate on ad banners, what the correlations between fixation duration on banners and overall fixation counts are, and the extent to which site visitors are able to recall details of ad banners and of the clip viewed. Using a Miramatrix eye-tracker to record YouTube viewers’ eye movements, this study showed that nearly all fixated at least once on an ad banner in a clip. However, less than 10% were able to correctly recall the ad content viewed. Nevertheless, about half of viewers were able to correctly recall clip details. Fixation duration on the banner and fixation counts on the clip are negatively correlated, but the relationship between fixation duration and counts on the banner was insignificant. This study sheds new light on YouTube advertising through the use of eye-tracking and advises advertisers to be attentive in selecting clips on which ad banners will appear.