So I tried downloading one of the titles and it had multiple video streams and on the last video, it stopped downloading. 

Is there a way to restart it without downloading all the other video streams that are part of a single title?  UPDATE: 

I noticed that when I went back to the r18 site it restarted to download again. What's going on? Should I keep my web browser (chrome) on the r18 site? 

Hi there. Not sure what's going on but just as a guess, if you cycle (ie. Change your cookies) when Jav-it is not expecting it, you may experience unexpected side-effects. It's best not to interact with R18/DMM while your downloading videos.