have you tried doing that with movies?Android file transfer doesn't work. I had to download a program called file expert. Now I can FTP files wirelessly to my galaxy. Love it more since I don't have to worry about cables.
but there are some items (I am in the military) that I cannot trust to transfer using the cloud.
estigall when you plug in your usb do you see up at left hand corner mtp application thats when you can tranfer your files i right click on file and sent it to my tabOI would think anything that you can't trust to use with dropbox for security concerns, I would be concerned with the Mac and the tablet as well.
I hope you're not using these devices for opsec materials.