Here is the thing..

I only want to download HD episodes of my favorite series.. (Lost, Mentalist, Tudors etc)...
the thing is that although those episodes exist lets say on piratebay, TED does not find those HD episodes thus not donwloading em...
Can u please improve the search engine?

I have the same problem and I wonder if its because they are looking for HD and the title has HDTV?? I hope they fix it soon.

That's exactly the problem. The naming convention used changed such that many HD episodes are now signified by HDTV instead of HD. Adding HDTV along with HD and 720p as accepted tags would be the easiest way to fix this. Hopefully this small change can get included in the next revision.

In the meantime you can adjust the file size range to pick up the HD episodes. Notice when you check the HD download box the corresponding file size changes. Just note this file size, uncheck the HD box, and manually re-enter the larger file size. Now it will search for the larger files without screening the tags for the keywords.