"TV shows are emerging as a new front in the war over digital media between Amazon.com Inc. and Apple Inc., amid their ongoing battles over electronic books and online music. Hours after Apple said Wednesday that it would begin renting some shows for 99 cents per episode, Amazon cut its price on a similar set of shows to 99 cents from $2.99. ... A price battle between the tech titans could help drive consumer interest in the nascent market for paid on-demand video over the Internet. But it could also drive away the media giants that Apple and Amazon are counting on to feed them with TV content. Some media executives worry low prices could eventually undermine the existing TV business."