Among today’s new DVD releases:”The Iron Lady” (PG-13): Meryl Streep disappears so uncannily into former British Prime Minister Margaret Thatcher that her performance overpowers this portrait of one of the most significant figures in 20th-century Britain. “The Darkest Hour” (PG-13): This lackluster sci-fi thriller boasts impressive special effects but little else. It tells the story of a group of Americans on a business trip to Russia when aliens invade. Extras include deleted scenes, a look at the special effects, commentary, and a short sequel that picks up after the movie ends.”Astonishing X-Men: Dangerous” (Unrated): This “motion comic,” with limited animation, is based on a popular storyline in the comic book series about mutant superheroes. It was written by Joss Whedon, the director of next month’s big-screen superhero film “The Avengers.”"Donald Glover: Weirdo” (Unrated): Glover, one of the stars of NBC’s comedy “Community,” proves his skill at stand-up in this special.”Dark Shadows” (Unrated): With a movie version due in theaters next month, two new releases each have nine episodes of the classic, gothic soap opera, plus “Fan Favorites,” with some of the most popular episodes, and “Best of Barnabas,” which focuses on the show’s most popular character, the vampire Barnabas Collins.Also new this week: “The Witches of Oz,” a miniseries update of the “Wizard of Oz,” about a fantasy writer who is transported to the world depicted in her books; “Good Night for Justice,” a Western starring Luke Perry; “Doctor Who: The Daemons” and “Doctor Who: Carnival of Monsters,” two classic storylines from the British sci-fi series, both starring Jon Pertwee; “The Terror Experiment,” a cheesy zombie film with a cast including Robert Carradine and Judd Nelson; “Being Elmo: A Puppeteer’s Journey,” a documentary about the “Sesame Street” character and the man who brings him to life; and “Into the Abyss,” director Werner Herzog’s documentary about a Texas death-penalty case.New to Blu-ray: “A Streetcar Named Desire,” the searing 1951 drama starring Marlon Brando and Vivien Leigh, in a special edition packaged inside a 40-page companion booklet; “Kate & Leopold: The Director’s Cut,” a cute romantic comedy with time travel, starring Meg Ryan and Hugh Jackman; and “Bounce” with Ben Affleck and Gwyneth Paltrow.