1. A method comprising: obtaining a query being a media portion; obtaining at least one media reference set being a set of media portions; obtaining a descriptors reference set being a set of local descriptors extracted from the at least one media reference set, wherein the descriptors are defined over a descriptors space; extracting descriptor space representatives from the descriptors reference set; calculating a non-parametric probability density estimation of the descriptor space representatives, given at least one of the media reference sets; extracting a set of query descriptors from the query; calculating for at least some of the query descriptors, at least one of their nearest descriptor space representatives; calculating a non-parametric probability density estimation for at least some of the query descriptors, given at least one of the reference sets, using a weighted average of the non-parametric probability density estimations of the nearest descriptor space representatives, wherein the weights are determined based on the respective distances in the descriptor space, between the query descriptors and the corresponding descriptor space representatives; calculating a non-parametric probability density estimation of the query, given at least one of the reference sets, by applying an operator to at least some of the calculated non-parametric probability density estimations of the query descriptors; determining a saliency level of the query, based on the calculated non-parametric probability density estimation of the query given the at least one reference set, so that a lower level of the calculated non-parametric probability density estimation is indicative of a higher level of saliency of the query; using the saliency level of the query as a criteria for selecting a sequence of media portions of interest; and generating an audiovisual media stream based on at east some of the selected media portions of interest, wherein any of the obtaining, the calculating, the determining, the extracting, and the generating are executed by a computer processor.