additions, except for the alteration, deletion, or substitution of
commercial advertising market research: *Provided*, That the
research company has obtained the prior consent of the advertiser
who has purchased the original commercial advertisement, the
television station broadcasting that commercial advertisement, and
the cable system performing the secondary transmissions:

*And provided further*, That such commercial alteration, deletion,
or substitution is not performed for the purpose of deriving income
from the sale of that commercial time.

(4) Notwithstanding the provisions of clause (1) of this subsection,
the secondary transmission to the public by a cable system of a
primary transmission made by a broadcast station licensed by an
appropriate governmental authority of Canada or Mexico and
embodying a performance or display of a work is actionable as an act
of infringement under section 501, and is fully subject to the remedies
provided by sections 502 through 506 and section 509, if (A) with
respect to Canadian signals, the community of the cable system is
located more than 150 miles for the United States-Canadian border
and is also located south of the forty-second parallel of latitude, or
(B) with respect to Mexican signals, the secondary transmission is
made by a cable system which received the primary transmission by
means other than direct interception of a free space radio wave
emitted by such broadcast television station, unless prior to April
15, 1976, such cable system was actually carrying, or was
specifically authorized to carry, the signal of such foreign station on
the system pursuant to the rules, regulations, or authorizations of
the Federal Communications Commission.