I do not own a smart phone. Mine is a rather stupid one - it can summon the police or a pizza, but cannot take pictures of them as they arrive. I do not repine - I have mirror-less cameras for that. I have a album of 8 x 10's of Neapolitan pepperoni surprise.
For those of you who do have the photophones and who insist on videoing themselves and others, there is a useful accessory just now on the market.
The Metz LED - 72 smart is an add-on LED array with 51 of the little glowing nubbins mounted on a metal mount. It plugs into the socket on your mobile phone and draws power from its own internal Li-ion battery.
It has several power settings starting at a full 72 Lux rating and then going down to a blinking mode. More than enough light to video with the phone or to light up a Subbuteo tabletop football game. The battery will go for some four hours on a full charge - and you charge it from a USB port on your computer in about 165 minutes.
Those of you who will be artists with this light will be artists and those of you who will be party pests with it will be party pests - the equipment does not make the person. But at least you will be brightly illuminated.