I didn't find this documented anywhere else, so I wanted to note that, if you want to use windows domain accounts in the authentication process for ovftool without specifying it interactively, you must specify the \ character using %5c, as in:
ovftool --acceptAllEulas --net:nat=mgmt-net --datastore=nfs-1 --name=Ubuntu-test Ubuntu.vmwarevm/Ubuntu.vmx vi://WINDOMAIN%5cAdministrator:password@10.10.10.100/dcName/host/cluster-name