You should not have a problem with reformatting the flash drive. I use a Mac and build and install stuff on my chumbies all the time.
On the Mac, "MS-DOS" and "FAT32" are the same thing.
Backup your drive on your Mac, then use the "Disk Utility" in the Applications/Utilities directory to reformat the flash drive as "MS-DOS (FAT)". If you're asked, make sure you use a single partition and Master Boot Record.
You should have no problem reformatting it back to a Mac-specific format later.
Thank you, Duane. You were "right on"! Formatting to MS-DOS allowed me to install the YouStreams Widget. I also had no problem in reformatting the Flash Drive as "Mac OS Extended (Journaled)".
Thank goodness YouStreams is Mac-friendly.