All standalone TedTalk apps I tried won't deliver HD quality video which this tv box deserves.
Tedtalk HD in iMediashare allows you to play the HD version beautifully. However, iMediashare works with wifi connection only, not working for wired internet. I asked the developer once about supporting wired internet, but I'm not sure they will implement it or not. iMediashare also give you Cnet HD version which you can't find in any standalone Cnet app.
OnAir Mediafly is also a comprehensive vidcast/audiocast aggregrator. It give you much more channels (both SD and HD quality) than iMediashare. It also works with LAN connection. Highly recommended.
I personally don't own this tv box, but another Amlogic-based tv box is arriving and I hope I can share more experience on the Amlogic box community.