Trying to play 4K content on the Vizio M-Series 4K Ultra HD Smart TV is challenging given how little 4K sources are out there. Playing 4K content from USB drives seems like a natural choice but unfortunately the Vizio TV doesn't seem to support most of the 4K video codec formats.
To make it worse, one time when I plugged in the SanDisk Ultra Dual USB Drive 3.0, the Vizio TV crashed, creating a purple mosaic piece of art on my screen. The only way to get out of this crash was to reboot the TV. This is something you would never see in the pre-Smart TV era.