It depends of what signal do you want to receive: ATSC and DVB are digital standards and you have blocks and scripts to deal with as you have seen in the webpage you linked.
DVB has a lot of different modulation and encoding possibilities and dealing with this in GNURadio is a bit of a headache if you do not know the exact parameters to begin with. You can also try LeanDVB
Analog television is a totally different beast and I don't know yet how to deal with it. IIRC, the next version of GNURadio has a MJPEG sink on the wishlist to help deal with analog TV signals.
Using RTL receivers you can try a windows only software: tvsharp.