It may be fake, but it is possible. All televisions have a number of local oscillators for super-heterodyne reception. With sensitive equipment, the radiation from these oscillators can be detected because they are not well-shielded.
This is the case, but this technique will not allow you to distinguish between my television which I have paid for, and that of my nonpaying neighbour which is 12" away on the other side of an internal wall, on the 20th floor of a towerblock with hundreds of televisions in it, from the street. Which is what the Television Licensing Authority (the BBC dont actually have any involvement in collection or enforcement) claim they can do.
