To elaborate, the ArchiveTeam distributes a very simple-to-use virtual machine image that you can run. When you do so, your machine will help download and collect from disappearing websites. I don't think they've got scripts for justin.tv yet, but it sounds like they are going to, so now would be a good time to get your VM ready.

It's easy, and the more people who run the machine, the more power the ArchiveTeam has at their disposal. I encourage everyone to give it a look.

You can get the virtual machine here: http://tracker.archiveteam.org/