A method and System for identifying repeat clip instances in video data. The method comprises partitioning the video data into ordered video units utilising content-based keyframe sampling, wherein each video unit comprises a sequence interval between two consecutive keyframes; creating a fingerprint for each video unit; grouping at least two consecutive video units into one time-indexed video segment; and identifying the repeat clip instances based on correlation of the video segments. The method can be used for both discovering unknown repeat video clips and identifying instances of known repeat video clips automatically. The method can be used to identify short repeat video clips from less than a second long to a few minutes, such as tv station logos, program logos, tv commercials which are widely used in news video and other daily broadcasting programs.