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.
Finding that piece of software around 2001-2002 was what allowed me to finally download a specific piece of, ahem, 'shareware', that was about 400 MB, zipped, that I would never have been able to finish on a 14.4kbps modem on a single very noisy phone line that usually dropped the call every 2 hours or so. It eventually took three days but the file came across uncorrupted. It wouldn't have been possible without the ability to resume downloads after dropped connections.
And that software download went on to allow me to start the path learning what I wanted to learn about, and that paved the way for my engineering degrees and thus setting me up for the last 20-some years. Wild how little pieces of the puzzle like that drive so much of your life.