This is fantastic. Thanks for writing this and having the code on github. I dug around the code as the permissions concerned me, but I didn't see it phoning anywhere except to your assigned torrent UI. I haven't decompiled the extension yet but assuming that goes well and matches the github source I see no concerns over the permissions and they make sense since you don't have a site white list (which I'd recommend as a feature request to limit permissions in the future).