Confirm download ability

One of the things that is the most annoying with PlayLater is that there are unreliable downloads out there, especially for third-party plug-ins and such. To be able to determine if it'll download it needs to be first in the queue. While being able to dual download would help with this a bit, it'd still be helpful if PlayLater would try to connect to the source if you asked it to and if it doesn't work maybe put an X next to the file so you don't try to download it again unless you think the source is working again.