I had to rewind the video when there was the guitar pedal ad you had to button through before returning the the menu (22:20) because I could not believe what I was seeing..... what the hell? That was weirdly over-intrusive.
You'd hope that ads would contribute to a Rock Band title that's not so pared down from previous ones in the series.
It unlocks that tone for use in the solo mode, it isn't any more of an ad than the tons of Fender and other name brand basses, guitars, amps, speakers, etc. that are all over the game. There are apparently a bunch of different tones to unlock.
Amikron's comments