Hi there and welcome
What is the make and model of the unit you wish to do this on?
The USB is not for recording but for playing content.
You will need to use an actual DVR for this, which connects to the TV and performs the recording
this is one such unit that will do this
When connected to your TV, you can record one program whilst watching another.
you can also pause live TV while watching it.
But you need a DVR in order to do this
If you would like any additional information or assistance, please do not hesitate to let me know.
Else if you can take a second to rate my service by clicking one of the stars at the top of the screen then submit, that would be greatly appreciated.