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This paper studies the possibility of using the encrypted video channel of widely used videoconferencing applications, such as Skype, as a carrier for unobservable covert TCP/IP communications. We propose and evaluate different alternatives to encode information in the video stream in order to increase available throughput while preserving the packetlevel characteristics of the video stream. We have built a censorship-resistant system, named DeltaShaper, which offers a data-link interface and supports TCP/IP applications that tolerate low throughput/high latency links. Our results show that it is possible to run standard protocols such as FTP, SMTP, or HTTP over Skype video streams.