How {does that|is that supposed to} work?
Or, more to the point, why on earth would anyone want to do it?How {does that|is that supposed to} work?
People might, indeed, want to do that (indeed, I've done it myself). However, since they will presumably be wanting to find the URL of a specific image (not 'images in general'Someone might want to find a post containing the URL of an image they want to re-use rather than re-upload, or possibly have to re-create as well.

I've just been playing. It is possible to include "[ url ]" or "[ img ]" (without spaces and quote marks!) as keywords for a search (along with other search words/criteria) - similarly, one can use ".JPG" (or whatever). That works, the only problem being is that it will catch links/images in quoted material within a post as well as within in the poster's new text.Someone might want to find a post containing the URL of an image they want to re-use rather than re-upload, or possibly have to re-create as well.
Is the search term syntax documented anywhere, e.g. how to search for A or B, phrases, exclusions, wildcards etc?