ted.com uses rtmp:// .flv streams. You can download or capture them without any problem:

FAQ: How to record/download/capture/save Adobe Flash .FLV video RTMP stream from embedded player

Replay Media Catcher can perfectly download RTMP .flv videos from Ted.com:
Tutorial: How to download free streaming talk videos from Ted with Replay Media Catcher


And you don't really need any streaming video recorders for this web-site. You can just click onto the Download button below the video and download MP3 audio or MP4 video.