Cablevision Systems said its iPad app has been downloaded more than 50,000 times since its introduction on Saturday.

Customers seem to love it, and Cablevision is clearly pleased with the response, but not everybody is happy.

Regional sports channel Yes Network said it believes Cablevision does not have the right to redistribute its content on the iPad. Viacom, which pulled its content from Time Warner's similar iPad app, is also reported to consider Cablevision's app to be a violation of its rights.

Cablevision believes it has inoculated itself against such charges, however, by virtue of the fact that it is not distributing video to the iPad via its broadband network (as TWC is apparently doing) but through its classic video infrastructure. For contractual purposes, the iPad is just another TV screen in the home. At least in Cablevision's view.

Through the Optimum App, Cablevision is delivering approximately 300 live channels, thousands of titles of video-on-demand, advanced searchable guide information and DVR management, Cablevision said.

Cablevision customers said the Optimum App for iPad has been the most popular app in the Apple App Store's Entertainment category since Sunday, and it is currently the 10th most popular free iPad app overall.

"We are very pleased by the strong and positive consumer reaction to the Optimum App for iPad, reflected by download activity, ratings and reviews," said Gary Schanman, Cablevision's senior vice president of video product management. "Our objective was nothing short of delivering the full cable television experience to our customers on an iPad in the home, and we are looking forward to continuing to enhance and refine the app, which has already become very popular with our cable television customers."