Give it any URL and File2HD will let you easily download the files that a web browser would load for that URL.
For instance, give it a Youtube URL, and you can immediately download the .MP4 file if there is a high-quality version of the video (it’s just an example. If Youtube’s AUP forbits this, don’t do it).
File2HD can be very handy if you have to use a browser that has no similar feature (Firefox has cool extensions in order to do so).