This particular screen test is interesting because Weaver reads for a scene that was infamously cut from the film: Ripley finding Dallas cocooned. It includes dialogue not present even in the director’s cut. Dallas tells Ripley that the alien ate Lambert.

Alien (1979) was scripted to have a scene where the xenomorph was almost trapped by Ripley and Parker in the airlock of the ship’s “B” level. It escaped but lost a limb in the process, leading to its acidic blood causing critical decompression. Due to budget restrictions, the scene was not completed, but here is a partial moment of Lambert reacting to the situation, which was filmed before the decision was made to leave out the scene entirely.

Another fascinating scene from Alien left on the cutting room floor. Ripley consoles a clearly distraught Lambert, and asks if she had ever slept with Ash. Another moment people remember from the Foster novel but not from the actual film. As you can see the scene was restored and remastered- it was seriously considered for inclusion in the 2003 Director’s Cut version but ultimately still left out.

Alien explained (1979) - Film Colossus