Actually, many (perhaps even most) TV USB ports don't provide power (or good enough quality power) for anything beyond basic thumb drives. It's also possible for ports not to offer power unless the right handshake is made by the device. Also, some TVs have a USB port which is only for diagnostic use, and can provide unsteady/harmful power output.

However, I'm guessing this device ships with a USB cable + wall wart for everyone else.