I haven't looked at processing downloads yet. If the content ends up in the browser, you can likely get at it with the ->content method, but I haven't implemented anything like downloads yet. Likely you can easily instruct FireFox to follow a link to an URI and not to prompt you where to save it.

Patches to add that functionality are welcome.

Update: Mozilla Development Center even has the Javascript implemented. This doesn't allow for piping the download through Perl as it arrives, but it's a start.