On Demand movie highlights

50 First Dates ½

(Encore on Comcast) “Groundhog Day” meets “Memento” meets “The Wedding Singer.” Hawaiian veterinarian Adam Sandler, in date-movie mode, falls for Drew Barrymore as a woman with no short-term memory: The gag is he has to woo her from scratch every day. The two stars play together charmingly — he gets her to focus and she softens his smugness — but dumdum comedy clutters up the fringes. (PG-13; runs through March 13)

Ty Burr

Tropic Thunder

(Free on Comcast) It only sounds like a Thai porno. Really it’s a war movie within a comedy. Five actors — Ben Stiller, Robert Downey Jr., Jack Black, Jay Baruchel, and Brandon T. Jackson — playing soldiers caught behind enemy lines in Vietnam actually wind up behind enemy lines and assume that somehow they’re still being filmed. Written by Stiller, Etan Cohen, and the actor Justin Theroux and directed by Stiller, the movie is usually very funny and especially where, powerfully surreal, Tom Cruise is concerned. He’s the heart of darkness in this Vietnam-film send-up, a movie star having the time of his life playing a war criminal. (R; runs through March 31)

Wesley Morris

Iron Man 2 ½

(Free on Comcast) Robert Downey Jr. returns as the billionaire military industrialist who keeps the world safe with his metal suit. This time he’s battling a Russian-accented Mickey Rourke and a cocky rival military contractor (Sam Rockwell). This movie is at its best when it’s breezy, playing up the idea of the CEO and the superhero as a vain rock star. But the heavier both the movie and the metal get, the duller they become. The talking and chemistry here are so good that the brawling feels mandated. (PG-13; runs through March 31)

Wesley Morris