The battle for the binge TV viewer is on.

Big pay-TV operators including Comcast Corp. and Verizon Communications Inc.'s FiOS are taking steps to vastly expand their on-demand TV offerings. In doing so, they are edging toward turf occupied by online players like Netflix Inc., creating a tug of war over where people turn when they want to "binge" on a full season's worth of programming.

Consumers...