Totally agree about that. I think those are what most of us saw (I was there, and the lights I saw coincided with the power failing). HOWEVER:

.. several of the cameras from the video were facing the ocean (i.e. the one at Larcomar, the mall in front of the sea, or the one at the airport, which is right next to the sea). Also, many people reported lights from either the ocean or from desert hills that lacked transmission towers or anything electric.

Although I'm still not totally sold on the idea of rocks emitting light, I hope I won't have the chance to verify it for myself, as the experience of an entire pitch-black city being illuminated with light arks in the middle of an earthquake was scary enough.

Having experienced the 6th largest earthquake ever recorded by a seismograph [1] I can assure you the lights I saw during that night were a lot brighter and higher in the sky, so power lines and transformers are ruled out. I was living fairly close to the epicenter (about 18 miles from the picture you can see in the wikipedia) and the lights were up for several minutes after the electricity went out.

[1] https://en.wikipedia.org/wiki/2010_Chile_earthquake