Im Having a Video issue

Hi, I'm from Chile, and im a nikon user since almost 2 years. I have a nikon D3100. My problem is when I record a video and i watch it on my laptop, there is a light purple spot, that appears (like the size of a pixel) and always in the same place, so that gives me the idea that can be something related with the sensor. I have proved that its not a problem of my Lid, paradoxically is that the pictures are with out this spot. I have also cleaned the sensor with the camera option, not manually. Do you know what this can be, thanks!

Hi Diego,
I would try a long exposure in still photography, to see if it may be dust on the sensor. My D7000 had some spots that only showed up in longer exposures. Why it would be there in the fast fps of video and not in still photos I can't explain, unless you are using a video dedicated lens. If that is the case it could be a spot on the lens.
Sorry I couldn't be more help.