You can't type as fast as it is needed url by hand, but that is not the purpose of this tool. You copy it from somewhere and paste it into invwget.
The intention to write it was, to have a tool, into that an url can be pasted, and which then (recursively) downloads files, beginning at that url.
So, if you, for example, have a lot of pages opened in your browser tabs, that you may wish to download recursively, just copy the url from the browser, paste it into invwget; then you can close your browser-tab and get the resulting downloads in the working directory, where you started invwget.
This way you can download a lot of webpages recursively easily: select the pages with the browser, download them with invwget.