Slow download speeds and stalling apps

I've had it happen multiple times with large applications, namely the Lion previews, Aperture and Final Cut. The app starts out downloading fine, then stalls and seems to get stuck, with the time changing from 'One minute remaining' to god knows how long.

I have tried restarting and pausing/resuming multiple times. I've repaired permissions and set up custom DNS settings through Google as well as looked into the Keychain access fix that some people reported, all to no avail.

I've included a short screencast to demonstrate: http://cl.ly/8E99

Help is very much appreciated.