Is this bad design? Ehh… It is persuasive design. TED ( or the designer) knows that if you want the video to start, you will find the play button. It’s in its logical place, just not highlighted.
By making the Share and Rate buttons stand out, they increase the chance they will be clicked, without decreasing the amount of times the video will be played – but- the most common action is no longer the easiest to find.