“Murderfest” (* out of four) was a tawdry horror thriller about five serial killers who broadcast their killings online to a live streaming audience and compete with one another to see who has the most murderous craft. Potentially satirical look at the dark web and online streaming is hamstrung by terrible production and filmmaking and gets dumb-and-dumber as it goes along. “Yawnfest” would be a better title for this trifle.