Just putting this here.
Yes I know, it's past game but it does show how fragile our defense organization is, with the poor communication and all.
So if it's true that that is De Gea's voice, then Shaw chose to ignore him.
To be fair to Shaw, he decided to follow the captain's pointing finger "order".
It's also a testament to Shaw that he is arguably the only player De Gea can trust in this situation because frankly Bailly could've easily cover the spot Shaw left behind but as usual Bailly don't have that "defensive vision" i.e. awareness of danger.
Than again, maybe he's actually saying "Go Luke, go!" which Shaw did, but their body languages and reactions afterwards (no I'm not an expert in reading body languages) seems to say otherwise.