"knowingly and with intent to defraud, accesses a protected computer without authorization, or exceeds authorized access, and by means of such conduct furthers the intended fraud and obtains anything of value, unless the object of the fraud and the thing obtained consists only of the use of the computer and the value of such use is not more than $5,000 in any 1-year period"

Injecting or replacing ads in other people's content on the wire: 'knowingly and with intent to defraud', 'exceeds authorized access', 'furthers the intended fraud'

Ad revenue from doing so: 'obtains anything of value'

Forget copyright infringement: a case could be made that CFAA applies here.