Secretary Clinton ran in to some problems with the weave pattern of the jacket she wore for her Mother's Day address to State Department employees. She looks all wavy:
You may have noticed, though, that this is the same jacket she wore for the Nuclear Nonproliferation Treaty Review Conference press conference last week, with the collar unbuttoned:
She doesn't look all wavy here. Same jacket, so what's the difference? The distance of the camera. When the camera was close to her for her recorded Mother's Day message, it was able to pick up individual lines in the weave of the fabric, but not so finely that they don't run together as she moves. For the press conference, the camera was further away, and even zoomed in to put her at approximately the same size in the frame, it doesn't pick up each of those individual lines - they blend together into a more uniform shade of gray.
I still wouldn't say you can wear a glen plaid with the cameras at the back of the room, but it does give you a little more flexibility.