Yes we know the reasons for this, and if you had of searched these forums you would of found many posts on the same issue. It is due to the way the Emumovies API works, in that if we dont hit it for a piece of media within 15 minutes, all the URL's we got at the start of the process are deleted, so when we get to downloading media from them, the URL's have expired so you get a 404 error returned. They are working on there API in hopes of fixing this, but we can only use the tools we are are provided with, and it is how it is currently. There are some workarounds in the current beta if you are not running that that may help to alleviate the problems, also dont do your entire collection in one go, as that may mean hours to get to a specific system, by which time those URL's will no longer work, so go platform by platform.