Right. That's the first time I've seen that. Blatantly, that is miming. My gut feeling tells me that the backing track to which he is miming is either taken from a studio recording or was taken from a previous performance, where he stood still and held the microphone at the same distance from his mouth throughout.
When you listen to the performance, it sounds note perfect. The fact that he is moving the microphone away from his mouth, then towards his mouth, then away from his head, while his vocals remain constant, is too much of a give-away.
When singers perform live, it is almost unmistakable. Within seconds, the audience know if a performance is live or not.
How Buble can come on a national radio station and call those who say he was miming, "are idiots", is beyond me.
By all means, mime. Mime till your hearts content. But when you get found out, don't insult those who found you out.
Shame on you Mr Buble.
At least Cheryl didn't claim her performance was live, when she mimed.