Saleen WebDownloader is a tool which can search for and download media from Flickr, YouTube, Google Images, Facebook, Picasa, PhotoBucket and WebShots.
The interface is a horrible mess - a browser window here, another pane over there, some barely noticeable tabs, various other controls scattered around with no clear organisation - but after a moment or two you'll spot a Search box at the top of the screen. Enter a keyword or two here, choose the site you'd like to search, and the results will be displayed in the browser window.
If you're searching for videos then you can locate the movie you need, perhaps start playing it. Once you're sure you have the right one, clicking the Download button will grab you a local copy.
Or maybe you're running a picture search? All your images should appear in a separate window (click "Select" if they don't). You can select all or some of these, clicking "Save selected" to grab a local copy.
And if you download so many files that you've lost track, simply click the Library tab. The interface is even more bizarre than the main window, but get past that and you'll find a list of everything you've downloaded recently, while right-clicking each file provides a range of useful options (Open/ Play, Add/ Edit Tags, Generate Frames, Locate WebPage, and more).
Its interface is dreadful, but if you can live with that then you'll find Saleen WebDownloader can reliably search for and download content from a wide range of sites.