I have Tor installed on my mac, and Tor-button installed on my Firefox (along with NoScript, BetterPrivacy, AdBlock, and RefControl).
By default, Tor disables plugins like Flash. From what I've read on Tor's website, this is because plugins run outside Firefox, and thus wouldn't route through Tor, revealing my identity (http://www.torproject.org/torbutton/faq.html.en#noflash).
When I use Tor (in default settings) to try downloading from SourceForge, it says that an external application is needed to handle the download. What external application is this, that firefox needs it to download files? I know it's possible to have Tor allow plugins, but then what information would that communicate to my ISP?
Also, I know Tor recommends using a Virtual Machine or LiveCD which redirects all internet traffic (not just from the browser) through Tor. Why is it necessary to have a VM or LiveCD to do that; isn't there a way to redirect all traffic through Tor on my native OS X? Or at the very least just re-route the plugins through Tor?