WATCHING A SCREENER of AMC’s Dec. 13 American Cinematheque mid-career tribute to George Clooney got me thinking — and not just because of the nagging sense that while we are roughly the same age, the actor-director-sexiest man alive has jammed far more living into his fortysomething years despite a bad back and “Batman & Robin.”

Then it dawned on me that this month represents something of a personal milestone, albeit one unlikely to be feted with any black-tie galas — namely, my 20th anniversary on the entertainment beat, having started out at the Hollywood Reporter in December 1986.

After 10 months at the Reporter (some things, apparently, never change) came the move to Variety, the Los Angeles Times, then back again. But the real eye-opener came from contemplating the wrenching changes that have beset the TV business during that quarter-life-span, reshaping the landscape in a way that barely resembles the one I encountered as a beard-free youth.

 Sounding a little like those rose-seekers on “The Bachelor,” this two-decade stretch as witness to TV history has been quite a journey, yielding a memorable array of sights, sounds and angry phone calls. More than anything, though, it has been a time to watch the menu of entertainment options simply explode — yielding an overwhelming volume of programming compared with the late 1980s, when Variety still could, and did, review every original TV production, a policy that would now require a small zombie army.

OTHER EPISODES and personalities leap out as the years flash by like “The Time Machine.” Here are some of the more vividly etched moments:

  • The Fox network’s primetime sign-on in spring 1987 with its customary restraint and good taste, throwing a massive shindig that include transforming the Hollywood sign to read “FOX” instead.

  • Several Lorimar distribution execs spending the night in jail at the NATPE convention, after being nabbed by Houston vice cops for allegedly touching the merchandise at a local strip club.

  • Visiting said strip club the next year and seeing a plethora of equally curious convention-goers — including conservative talk host Morton Downey Jr. — crammed into the place.

  • Fox stealing the Emmy Awards telecast, pro football and a dozen affiliates from the shell-shocked networks.

  • NBC Entertainment whiz Brandon Tartikoff literally swearing on a stack of Bibles, with an actor playing a priest, that he would never order another Geraldo Rivera special.

  • The indomitable Tartikoff, near death at age 48 from Hodgkin’s disease, calling from his hospital bed to discuss the merits of a piece I’d written, only to have the nurse intervene and demand he hang up, fearing he was too ill to be working the phones.

  • Tom Arnold calling to complain about ABC’s mistreatment of his sitcom “The Jackie Thomas Show” when, after about 15 minutes, then-wife Roseanne blurted something out, having apparently been listening on the other line the entire time.

  • Veteran producer Edgar Scherick passionately chewing out a panel of academics at then-Sen. Paul Simon’s forum scolding the industry regarding TV violence.

  • Lightning round: The fin-syn rules go away. The WB and UPN are born in a flurry of petty sniping. Indies New World, Orion and MTM disappear. Disney merges with CapCities/ABC, and Westinghouse acquires CBS weeks later.

  • Brandon Stoddard, having happily vacated ABC Entertainment’s hot seat, saying that top network brass usually last only three or four years in those jobs “because that’s the average sentence for a white-collar criminal.”

  • TV reporters swarming around then-ABC Entertainment prez Jamie Tarses during the semi-annual press tour, barking questions as if awaiting release of the Pentagon Papers.

  • NBC West Coast chief Don Ohlmeyer calling me “the anti-Christ,” then causing a stir by referring to Mike Ovitz the same way in Time magazine.

  • Receiving an anonymous tip before the original “Survivor’s” hugely hyped finale that “the guy who wins” had just been arrested for abusing his adopted son. CBS circled the wagons, but Richard Hatch was indeed arrested and did win.

  • Writing a self-referential column shortly before the holidays, and hoping, like that new NBC sitcom, for another 20 good years.