Many Windows PCs have more than one drive. I’d like to be able to specify where downloads are stored on my Windows system so they don’t take up space on my C: drive.
There’s already an existing suggestion discussing an option to specify/change the download target directory from within Plex. I suggest you comment/vote in that thread in order to help us avoid distracting or cannibalizing votes. Unless I’m missing some unique aspect of your suggestion I’ll close this thread as a duplicate.
As an alternative you can replace the current location with a symbolic link to anywhere else you want.
2023 clean-up: duplicate; requested behavior can already be achieved using symbolic links (depending on the host platform)