Copy All Links copies a human readable list of all the links associated with the current resource. If you paste this in a plain text document, you will normally get the Markdown formatted version automatically. If you paste it in RTF or HTML field, you will get a RTF or HTML field respectively.
This can be useful if you are writing a report or want to share information with colleagues.
You can also apply the links in a different Hookmark window, using Hook to Copied Links. This is very useful when you want to copy all the links from one resource to another.