Where may i find an external search tool for windows xp to search WITHIN an application?

For example, if i wanna search through my Firefox bookmarks, and find a particular bookmark, which program would i use to do such a search? IF i wanna go through something inside an application, such as a internet-based program that searches youtube videos for content, and downloads the videos, how would i pick and choose through hundreds of videos? I want a search command that is preferably freeware, but i will pay for one if i can't find one freeware. Please advise.