Go to the start page dctp.tv, and find the URI of the video you want to download. From the Flash caroussell, the links are a little hard to extract. Look at the source and look for URLs starting with "/filme/".
You'll also find the cloud front URL there, or visit: http://dctptvv2.appspot.com/streaming_servers/
Then visit the page of the film. In the source of that page you'll find links to iphone video versions that leak the film's id. Use that id hash and complete the string for the playpath like below, everything else mostly is the same.
rtmpdump -o singer_video.mp4 --host "s2pqqn4u96e4j8.cloudfront.net" --playpath "mp4:6f3b2bb4cdeb48d2a03ee20c2a6f2405_iphone.m4v" --protocol 3 --tcUrl "rtmpe://s2pqqn4u96e4j8.cloudfront.net/cfx/st/" --app "/cfx/st/" --swfUrl "http://dctp-front.dctp.tv/dctptv_v91.swf"
Above, the interview with Wolf Singer about the inner architecture of the Brain, "Orchester ohne Dirigent". Highly recommended, as everything Alexander Kluge does.