The iPhone dosen't support Flash video - which the main browser video versions of most web - based video sites, such as www.ted.com videos are formatted as, HOWEVER, the iphone happily plays and streams .mp4 video! So finding the .mp4 video link from sites such as www.ted.com videos actually do stream nicely OTA (Over The Air) directly to the iPhone. See screenshots below ;-)
To do this:
Browse to the video site on Safari on the iPhone. Select the 'RSS' feed links on the iPhone, you can then stream OTA .mp4 video or audio directly from sites like www.ted.com. The iPhone uses an online feed reader to do the conversion for it: http://reader.mac.com, which then displays a Quicktime plugin icon, selecting this icon will then stream the audio or video directly OTA to the iPhone YAY!
Be aware that streaming media does not store it on the iPhone - if you want to watch/listen more than once, it's best to use the iTunes links on your PC to download the video/audio to iTunes on your PC, then sync the downloaded files to your iPhone for offline viewing!