Investigators testing arcade games to see if they are winnable VIDEO

"All of the games are rigged at carnivals."
That's categorically wrong, as people win things at carnivals all the time.

Isn't the oval shape the whole point? I just assumed that it was.

While not all claws are rigged, especially ones with cheap prizes in them, the ones with stuff like iPhones and $100 gift cards are automatically rigged. The plastic container is physically impossible to get a grip on with a low-force claw with smooth edges; if it were a rectangular box with nothing sticking out, it would be physically impossible to get it via claw machine.