9. The method of claim 1 , further comprising: selecting a first metadata from said at least a subset of said collected metadata; searching for at least a third multimedia data element having said first metadata; comparing said first multimedia element to said third multimedia element; collecting metadata associated with said third multimedia data element if a match is found between said first multimedia data element and said third multimedia data element; and adding said metadata associated with said third multimedia data element to metadata of said first multimedia data element.
10. The method of claim 9 , wherein comparing said first multimedia element to said third multimedia element further comprising: generating for said third multimedia data element a first signature and a second signature, said first signature is a robust signature; and comparing between at least a first signature of said first multimedia data element and at least one of a first signature and a second signature of said third multimedia data element.