The rtl-sdr as a software defined radio actually does not have enough bandwidth to receive a PAL or NTSC signal properly. PAL and NTSC signals require more than double the 2MHz typical bandwidth of the rtl-sdr. But, a decent black and white signal can still be obtained by using some of the luminance part of the signal. As only part of the signal is sampled, resolution will be lost. Also, as sound is broadcast on a separate frequency, a second rtl-sdr dongle will be required to receive the matching audio.
On YouTube, users Superphish and ek6rc have posted videos showing TVSharp in action.