LED lights "popcorning" (flashing on and off randomly)
Your dimmer and LED lights are incompatible. 

In the off position the dimmer is leaking a small current to the lights, this is enough to charge the smoothing capacitors in the LED drivers, once charged to a sufficient threshold, the circuit is able to drive the LEDs and drain the capacitor and the process starts again.

See answers to other questions about LED Blinking

See


Dimming LED lamps with ordinary dimmers - Big Clive
How to FIX Flickering LED Lights &amp; LED lights that won't Turn Off with Dimmer Switch - Vince