The poster of the video , George, tells us that it cannot be anything other than a phone because of the way the lady is holding the object. Yes the way the hand is cupped around it , is similar to how some people hold their phones but not everyone holds a phone in this way and I know I don't, so there IS the possibility of it not being a phone right there! But we have already been through that thought process anyway haven't we :P
It does look like a phone after George shares us his thoughts on it before showing us the footage, thereby colouring perception of the event. But is it a probable explanation? There are other things it could be like a hearing aid as others have suggested, but you cannot even see the object clearly , so you can't really come a reasonable conclusion on what it is, in my honest opinion and 2 pence :)