It's a snipet of a clip - there's not enough information to go on to determine a lie by what's presented
Everyone that says they can tell by looking at him is either lying or mistaken and probably has prior knowledge about the issue
I'm just going to assume people wouldn't necessarily want to clarify how they know he's lying based on 10 seconds of body language because they have no real answer - at least not one backed by any definitive evidence
It's probably a lie anyway though