Can censorship make a movie-going experience more tolerable? The original running length of Jake Kasdan’s Sex Tape is 95 minutes, but its Indian, adult-rated version has lost four minutes and a few seconds. Scenes of rigourous hip workouts by lead actors Cameron Diaz and Jason Segel have been left to the imagination, as have flashes of nudity and suggestive photographs, but the frequently colourful language stays. What cannot be shown can at least be verbalised.

The result is a slightly trimmer but still overlong comedy that has the look and feel of an extended sitcom. Diaz’s Annie and Segel’s Jay attempt to rekindle their pre-parenthood, absolutely amazing and astoundingly awesome sex life by recording a three-hour session featuring every single position in The Joy of Sex. Thanks to the twin wonders of the iPad and a screenplay-writing contrivance, the tape is leaked to a handful of friends and acquaintances. Jay and Annie must erase all evidence of their adventure before it gets uploaded onto the internet (cue in the movie’s second major plug, for the pornography website YouPorn).

The encounter with a businessman played by Rob Lowe, who is hoping to fund Annie’s mothering blog and receives the sex tape by mistake, isn’t half as funny as the scene with Jack Black’s YouPorn boss, who delivers a homily on the joys of smut. Sex Tape advocates profanity within the scared institution of marriage, but the writing isn’t bold or witty enough to make this point effectively . The start-stop screenplay scores in some places, but the episodes are as hurried as a knee trembler.

The off-the-wall energy needed to justify a premise more suited to an independent feature than a multiplex movie is centred on Diaz and Segel' calisthenics. Blessed with sensuality and ample goofball charm, Diaz fares far better than her eyeball-rolling co-star. She carries off her often silly lines with enthusiasm, and retains her dignity despite being put in one unenviable position after another.