That's why sandboxie or some other sandbox app is handy. Just download and install inside the sandbox and then just scan that box. Takes seconds instead an hour or more and you can easily/quickly browse every folder and file that changed. If it seems legit then you can do it for real.
It sucks we are in an age where that is something that has to be done, but it really is the best bet for dealing with unknown files.
Been trying sandbox out and think it works nicely. It stills allows you to do a download and save it to your hard drive if you wish, which is nice. Downloaded some gifs and it was no problem using sanbox.