The phrase "to improvise every scene" means to make up or create each part of a performance or situation without any previous planning or script. Full definition
Not a movie so much as extended takes edited together (by no less than 3 credited editors) of improvised scenes from previous characters in another Judd Apatow movie. (metacritic.com)
It's the classic dysfunctional family gathering, shot in the InDigEnt model, with handheld digital camera, practical lighting, lots of group scenes and the camera bobbing through what looks to be like controlled chaos of at least partially improvised scenes. (seanax.com)
The play's cast of community performers and professional actor, Duncan Rennie - who plays Jesus - are currently working on improvised scenes as well as writing parts for their own characters. (premierchristianity.com)