1. A system for enabling a user to search from a user computing device for content stored in archive copies of data files, based on multi-dimensional indexing of the data files being archived, the system comprising: a user computing device comprising one or more processors and corresponding computer memory and further comprising one or more data files; a secondary storage device for storing archive copies of the one or more data files, wherein each archive copy is stored offline relative to the user computing device; an indexer, which is configured to execute on one of (a) the user computing device, and (b) another computing device comprising one or more processors and corresponding computer memory and further hosting a media agent, wherein the indexer is configured to index content attributes of the one or more data files in the course of the one or more data files being archived to respective archive copies, wherein, for any given data file being archived to a respective archive copy, the indexer identifies content attributes of the given data file, including at least one of: textual content, picture content, video content, and audio content, and wherein the indexer is further configured to: (a) generate a searchable content index of the identified content attributes relative to smaller portions of each archive copy comprising the respective indexed content attribute, and (b) associate the content index with the respective archive copy; and a search filter that is configured to search in the content index for one or more user-supplied search criteria, and wherein the search filter is further configured to present to the user a fast-forward progression through a plurality of smaller portions of the respective one or more archive copies, wherein each smaller portion in the plurality of smaller portions satisfies the one or more user-supplied search criteria, without restoring the respective one or more archive copies in their entireties to the user computing device, wherein to present the fast-forward progression, only the plurality of smaller portions that satisfy the one or more user-supplied search criteria are mounted to the user computing device, and archive copies and smaller portions thereof that do not satisfy the one or more user-supplied search criteria are not mounted and remain offline to the user computing device.