“Kingdom of the Spiders,” a little-known 1977 thriller starring William Shatner and Woody Strode, is now available on DVD thanks to the Shout Factory. A B-movie riff on Hitch’s “The Birds,” it features Shatner as an Arizona veterinarian fighting killer spiders who are taking over a small town. It takes a while for the action to kick in (a lot of time is wasted on the vet’s romantic life), but when it does watch out.