I can take a subtle hint.....
I'm not familiar with the references to Linconite and Bentonite (U.S. trade names?), but I get the general idea.
Is it overkill? Probably not.
As the frequency goes up grounding becomes increasingly critical in HF applications. At upper UHF frequencies and above, even a right-angle bend in a regular conductor can introduce enough inductance to render a traditional ground ineffective.
Although a normal analog TV video signal is limited to a bandwidth of around 4.2MHz (U.S. system), digital processing is a whole new ballgame. The short rise-time and square-wave nature of digital pulses means that the signals are extremely rich in harmonics. Add that to the high sampling rates necessary for digital TV, and you could easily be dealing with frequencies up into the GHz range.
At the satellite station where I worked we had C-Band up/down links operating at 3 to 6GHz (3000 to 6000MHz). Grounding on that equipment was also by a complex array of rods, mats, and copper straps. There's the point you made about using flat straps to increase surface area to help deal with skin effect, and also the point that it's necessary to minimize any inductance in the ground path. In many cases this would mean parallel straps. (As an aside, normal coaxial feeders start to become very inefficient at these frequencies, hence the use of waveguides.)
At Ku-band frequencies (12 to 14GHz) used extensively for satellite TV these days, the problems become even more pronounced, so much so that it almost becomes black magic!
As has already been mentioned, yes, you should most definitely bond this ground system to the electrical supply ground.