When I click a download button, I get a popup-dialog like this:
If the file is large, I want to download it by
wget -c URL.
Right-clicking download button to select
Copy Link Location doesn't work.
How to copy the download link to clipboard?
It depends on how the download is set up.
With certain downloads, the download is initiated with a form
But there are some sites that use a single-use URL, or a cookie containing a single-use token, that prevent multiple download attempts, so capturing the download URL via the HTTP request is useless. In such cases, you need to look at the page source to see where you can capture the download URL before the download is initiated. Often, you can find the download URL and/or security token in the page's JS. Otherwise, it's typically found in the response from an AJAX service that the JS requests. Or, you may have to analyze the JS source and watch specific variables to capture all the download request components without actually triggering the download.
You can install Firefox's FlashGot addon. It will add extra option to this popup-dialog. And you even can customize it - go to FlashGot Options dialog and press "Add" button to add custom "Download Manager", which actually can be any script file to do whatever you want - for example (on Windows) select bat-file with single-line command