virtualbox.org

i want to run virtualbox off of a usb flash drive with the vitual hard drive files being backed up to the cloud, is there any way to access the files on the virtual hard drive individually so they can be individually backed up to the cloud instead of having to back up the entire hard drive every time?

What do you mean "individual files". You mean files belonging to the guests filesystem? If that's what you mean then VirtualBox wouldn't be involved, it knows nothing about guest filesystems. Any drivers for remote storage would be a matter for the guest OS.