No one ever said putting on a show was easy, least of all the names (a lot of them famous, quite a few not) on compulsively watchable view in The Sound of Musicals. Channel 4's reality-TV probe into the world of art, commerce, and high kicks is sure to be catnip to theatre folk the world over, even if the sight of Broadway actor-turned-Chichester "star" Christopher Fitzgerald walking his tentative way across a tightrope in his role as PT Barnum soon becomes a visual metaphor for the performer's ever-precarious chosen profession.

Beyond being made in the 1930s, being a British production, being a musical and two having the same director, nothing links these four films. But the randomness of this double DVD set brings bucketloads of charm.

How many times can a director re-work the same show and still come up with something fresh, gripping and memorable? This is James Brining’s third version of Sondheim’s killer thriller musical Sweeney Todd. He produced an award-winning version in 2010 at Dundee Rep. He turned to it again last month for his first production since becoming artistic director at West Yorkshire Playhouse. Now, he has re-worked it for the in-the-round confines of the Royal Exchange, initiating a trans-Pennine collaboration between the two theatres.

Forever breaking into song and dance, musicals are fun, fun, fun. They are primarily what folks go to for uplifting entertainment, are they not? Actually, many of the best aren't anything like that simplistic. Opening at the Young Vic last night, The Scottsboro Boys is no mere barrel of vacuous laughs, though it is comical and buoyant along the way.

“Love and pain is like peace and war - you want one you have to have the other.” It’s a line that pretty much sums up From Here to Eternity. The title of James Jones’s novel and the classic movie which it spawned gets rather lost in the new musical from Tim Rice, Stuart Brayson, and Bill Oakes.

Once upon a time, there were two cultures, and they were at odds. A forested wilderness stretches between the kingdoms of Sealand and Lagobel, as we glean from the childishly-drawn, giant map that serves as a front cloth for the NT's new musical spectacular – directed by Marianne Elliot and opening in the Lyttelton last night. The map shows, on one side of the wilderness, Sealand’s coastal realm with winding rivers and a chateau bristling with turrets, all in shades of blue.

There will be some who will sneer at this film, but ignore them. Director Dexter Fletcher has fashioned a wonderfully enjoyable movie from a play by Stephen Greenhorn (who also wrote the script), in which a good-natured story about family, love and friendship is set to the music of The Proclaimers.

They called Rita Moreno the triple threat – she could dance, act and sing. But even her spirited performance as Anita in West Side Story could not satisfy United Artists: the doomy low notes of "A Boy Like That" were considered out of her range, and the number was ghosted by Betty Wand, one of the scores of unknown singers who rescued on-stage stars from ignominy.

Having boundaries actually sets us free. So Neil Armstrong's wife argues. She is dogmatically keen to stop her husband rocketing off to the moon in the first scene of The Lightning Child – a groundbreaking show in so far as it's the first musical to premiere at Shakespeare's reconstructed wooden "O", opening last night. Armstrong (Harry Hepple in a space suit) does not agree with his spouse's imposed limits, however. A lunar voyage is, he says, his chance to become sublime.

There’s a song in the musical version of Legally Blonde, in which peroxide ditz Elle celebrates her impending good fortune. “Oh my god, oh my god, you guys,” she sings exultantly as she prepares to accept her beau’s proposal of marriage. Since leaving the role at the start of 2011, Sheridan Smith has continued hollering the words more or less non-stop. Oh my god Trevor Nunn just texted to offer her a part. Oh my god Dustin Hoffman just left a voicemail.