This should paste a list of the filenames of all selected files, one per line, in the order in which they appear in the Finder. If it is set to Rich Text, this technique will not work: you will get a document containing the actual files rather than a list of their names! (Menu Bar: Format>Make Plain Text/Rich Text). Make sure that it is set to use Plain Text and NOT Rich Text. If it doesn't say 'Copy files' but just 'Copy you've accidentally deselected the files reselect all, and try right-clicking again. Right-click on the selected files to get Contextual Menu and choose 'Copy files'. Open a Finder window containing the tagged files and Select All That will import and copy those images very neatly.Late to the party here, but this is something that has been bugging me too - and I eventually came up with a run-round for tech-shy people that requires no line-command coding, just ordinary Finder commands and SimpleText. In your case though, after you do the search you can simply use Quick Look or Finder preview (View, Show Preview) to look at the images and drag the ones you want to import into Photos directly into Photos. You should see a + mark under the cursor as you drag, indicating the items will be copied, not moved. Optionally, you can just drag some of the files onto your Desktop even without unarchiving. So create a new folder in another Finder window, and then hold the Option key down and drag them all to the new folder. To delete the files in the Trash, choose File > Empty. Or select the file and choose File > Put Back. To remove a file from the Trash, click the Trash to open it, then drag the file out of the Trash. Or select one or more files and choose File > Move To Trash (Command-Delete). Now you don't want to move those files, right? You want them to stay in ~/Library/Messages/Attachments so as not mess up your Messages app. To move a file to the Trash, drag the file to the Trash in the Dock. You can do that by selecting the first one and then Command+a.

Or, if you really want everything something like 'File Size is greater than 0 KB' will work. You could do 'Kind is Image' for all images. There are two ways to select multiple adjacent files on Mac. Then enter some search criteria that will get you everything you want. To do so, select File > New Finder Window in the menu bar (or press Command+N on your keyboard).

At the top you should see 'Search:' and then 'This Mac' and 'Attachments.' Make sure you select the latter so you are just searching in this folder. Go to the Attachments folder in the Finder.

One way to do that is with a simple search.

Select all files on mac