At one point in his demo, he uploads a file but terminates the upload more or less halfway. Then he begins downloading the file - which only progresses to the point it had been uploaded, and subsequently stalls indefinitely. And, finally, he finishes uploading the file (which gracefully resumes) and the file download (which is still running) seamlessly completes.
I found that particularly impressive.
(also a great app to download everything you wanted from a site, regex selections, etc.)
Makes several connections and downloads chunks in parallel, for some sites with limited upload (their, your download) speeds per session it really speeds up the downloads.
Sadly, not much development recently (9 months ago was the last commit)