I am using Windows 7 as host OS and VirtualBox 5.0.10 and installed Ubuntu 14.04 LTS. I already installed the guest extension pack and still I am not seeing any connected USB devices in Ubuntu guest. I tried to add VBoxUsers group also but terminal said VBoxUsers as no group found. I used following code:
~$ sudo usermod -a -G VBoxUsers <usrName>
Please help me friends.