The original Heberw text can be found in קריינא דאיגרתא volume 1. Here is my translation.
1 Nisan 5735
See the Rambam z"l in Hilchos Avodah Zarah, Chpt 2, Halacha 2 who explains the prohibition to read books which have material relating to avodah zarah (idol worship) and also that it is prohibited to see the pictures in them, for the verse says "Do not turn to false gods," even if are not turning to worship them, but just to see them (as we find in Toras Kohanim on Kedoshim). After this he writes as follows: "Regarding this it says 'Lest you investigate their gods and ask how did the other nations serve [their gods]. You should not ask about the way they served, in which manner was it, even though you are not doing that service yourself. [Asking these questions] causes you to turn to [these activities] and to do like the did as it says [in the Torah] 'I will also do as they did'".
We can learn from [the words of the Rambam] to all types of sins. If a person begins to interest himself in them to know what they are, in the end he will be dragged after them and rebel against the Holy One Blessed is He, may Gd protect us.
And now what can we say regarding the impure monster called "television"? On it, the eye can see all the abominations in the world (idol worship, sexual perversion, murder, etc) with total explicit detail of the actions and the people committing them. Coupled with this there is intense propoganda and shocking motivation to live a life of debauchery and lawlessness and to throw off the yoke [of Heaven] Gd forbid. The Satan dances there, for it gives him a great power to draw people Gd forbid.
It is incredibly obvious that watching that impure device is a great danger to a person's entire Judaism. Even a person who only watches occassionally has already cooled down his faith and his fear of Heaven Gd forbid. Someone who accustoms himself to watch it has emptied himself from any shred of faith or fear of Heaven and all the good inside of him. He has turned himself and destroyed his praises Gd forbid.
It is already well known in the world from experience that a person who puts his eyes on this impure device will turn into a evil person who throws off the yoke [of Heaven] Gd forbid. One who desires to guard his soul will distance himself from this, for in the end it will make him foul, for it is destruction.
Now we have heard that there are some people who strictly observe the laws of Torah and they themselves - as well as their older children - would never enjoy Gd forbid watching this impure device. However, they allow their young children to visit neighbors and to watch there (or they do not rebuke their children for going over to watch). They say "He is only a child, he is playing around. This device will not harm him."
The truth is this is a grave mistake which could be considered willful [disobedience of Gd's commands]. Really, it is the exact opposite. For children, the danger is doubled and redoubled. The desire to be curious and explore ([as the Torah says] "I will do like them") is very powerful for children. (A child's entire development and the way he lives his life is primarily based on this desire to do like other people do). When a child sees every kind of misdeed it is like "education" and "instruction" that he should also act this way. Additionally, a young person etches everything he sees clearly into his imagination (specifically what he sees when he is excited). These images will be etched into his memory for his entire life so that even if he merits to cling to the Torah in a place of Torah, nevertheless his soul and his Judaism will bear the bitterness of those abominable images which are engraved upon his memory just like life. This will cause him to be confused in his faith and bring shocking challenges upon him Gd forbid.
There is no doubt that there parents have a great requirement to supervise their children carefully so they should not have any contact or any glimpse of this impure device in order to save them from destruction.
In the merit of doing this, they will merit to see their children and their childrens children who learn Torah and keep the commandments. They will enjoy much nachas of holiness and in everything they turn to they will be successful for good and for blessing.
We wrote and sign for the sake of the Holy Torah and hope for mercy from Heaven and for the complete redemption soon in our days.
Yaakov Yisroel Kanievsky (the Steipler z"l)
Elazar Menachem Man Shach (Rav Shach z"l)