I need to test this later as I only have access to an unprivileged account at the moment, but based on comments online (https://stackoverflow.com/a/11917816), C:\Windows\Temp (%systemroot%\Temp redirects here, and is the folder Skype accesses from, is write only for unprivileged users (FILE_ADD_FILE).

Preliminary testing shows that I was able to write there with out any problem. No way for me to read it at the moment though...

Edit: As noted by another user here, yes, it is writeable. https://news.ycombinator.com/item?id=16367722