The CM7004 will not allow you to watch a recorded program while it is recording a new program. You must wait until the unit is finished recording. Then you can choose a recording to watch.
Please note; The CM-7004 has been designed as a Digital signal to Analog signal converter. Primarily the CM7004 is used to accommodate older Analog TV's that do not have an HD ATSC tuner, or a Digital display that does not have a Tuner installed.
Secondary to that, it also will record programs. This is an economy set top box and has limited Recording options.