1. A video search method, configured to a video search engine, comprising: receiving meta-data of a query clip, wherein the query clip is a part of a video, the meta-data comprises a first index tag and a first semantic pattern, and the first index tag is assigned by transforming features extracted from the video; retrieving one or more candidate clips from at least one video database according to the first index tag, wherein the query clip and the candidate clips are converted into a same format; and comparing the first semantic pattern with a semantic pattern of each of the candidate clips and adjacent video clips, and marking each of the candidate clips as a returnable video clip or a non-returnable video clip according to a comparison result, wherein the candidate clips marked as the returnable video clip are served as a query result matching the query clip.