It's not hype. It's very true. The only problem with that system is that they say you can parlay your wins into thousands. But that would only happen if you got that one number correctly 8 or 9 days out of 10. That's really difficult to do.
I see those ads all the time. Sometimes they're disguised under titles that are misleading. One of them is on those sidebars claiming you can make 5,444 bucks a week.
Here's an example. Say you pick 3 as the key number, and hope no doubles come out with the 3 in the winning number. So here's what you would play for that draw:
013 023 043 053 063 073 083 083
123 143 153 163 173 183 193
243 253 263 273 283 293
453 463 473 483 493
563 573 583 593
673 683 693
A total of 36 sets. As long there are no doubles, and 3 was your key number, you win a box bet, unless you play each set all six ways, but then it would not be cost effective, unless you could correctly pick the key number every day.
To prove to yourself that this works, just pick any 3 digit number with a 3 in it, and you'll see it somewhere in the list above. Just close your eyes and pick any 3 digit number.