Looks great, I used for a few minutes and it's very intuitive! I did try to download my video on Firefox and after waiting a few minutes I gave up, maybe you got an error in your tracker?
Thanks! The video transformations can be a bit time-consuming (especially right now as there is quite a bit of traffic from hackernews) - I'll add a proper loader so you can see how much time is remaining. Admittedly I haven't tested much with firefox, i'll check if there is an issue with the download itself.