I have tried to watch TED talks on my Roku, but the quality is terrible. Many of the videos (especially the older ones) freeze, cannot be rewound, and have audio sync problems. According to the Roku support forums, the TED channel is an unofficial hobby project maintained by a Roku engineer in his spare time. He says the video problems started after ted.com changed their video formats. He can't afford to pay for transcoding/serving of Roku-friendly videos.
Thanks for the link! I didn't know an official TED channel had been released.
Note that most of the comments on that Roku blog post describe the same audio sync and video freezing problems I experienced (and that have been reported in the Roku forums since early 2011).
Here is a (May 2011) Roku forum post from Dylan Doxey, the developer of the unofficial TED channel. And I was mistaken: he is neither a Roku nor TED employee.
The previous TED channel was based on the TED RSS feed and assumed that all the
videos would be Roku compatible. Sadly, starting some time in April 2011 TED
stopped publishing videos in Roku friendly encoding. After being flooded with
support requests, the TED people contacted me and asked me to make it clear on
the channel description that the TEDTalks Roku channel is not built or
supported by TED. They also said, "We're working on the encoding issues that
are causing the poor performance on Roku; this platform just wasn't on our
radar when we built our encoder."*
Just to be clear, TED is no longer publishing videos in a Roku friendly format.
If some long period of time goes by, I may consider downloading the videos,
re-encoding them, and re-hosting them. However, I'm not sure my humble server
will support hosting video files for some 55K+ channel subscribers. The TED
servers are much more capable of handling that kind of demand.*