The well-established usage is “on TV” rather than “in TV.” Native speakers of English would say “I saw you on TV last night” rather than “I saw you in TV last night.” The same is true when “TV” is spelled out as “television,” as in “The beleaguered candidate appeared on television last night to appeal for sobriety in the election campaign.” This idiomatic preference for “on” is in keeping with the general rule that the preposition of place and location to use for surfaces is “on,” and it is conceptually intuitive and logical to consider the TV screen as a surface.
Some people, of course, mistakenly think that it’s acceptable to use “in TV” instead of “on TV.” This is likely because when the word “TV” or “television” is used as a modifier, say for such terms as “TV debate” and “TV newsroom,” the appropriate preposition for linking such terms in a sentence is “in.” This, for instance, is the case in such sentences as “The candidates became violently adversarial in their TV debate” and “There was chaos in the TV newsroom when the derogatory document against a candidate turned out to be spurious.” In these cases, however, the true object of the preposition is not “TV” but the nouns “debate” and “newsroom,” respectively, and these nouns require “in” and not “on” to link them to the sentence.
This explanation for “on TV” as the preferred usage also applies to “on radio” and “on the Internet,” which are the accepted idioms for these two other communication media. It doesn’t apply to “the movie,” though; the widely accepted usage is “in the movie,” as in “The child star appeared in the movie as the young Rizal.” There could be other instances similar to this that may require the preposition “in” rather than “on,” so it’s advisable to knock off the phrase “and whatnot” in the last sentence of your question above.
