I'm looking at both depending on what I'm playing. If it's a particularly hard part involving the left hand I'll watch that, but halfway through the lead if I have to find a pinch harmonic, I'll glance at my right hand... then back again.
It just depends on what you're playing.
On easy stuff I just find myself looking around at random objects.

Although, performance wise, it's a slightly different story.
If you know you're being filmed or you're playing on stage... there's a certain presence you have to convey. So that means either sitting up straighter, looking more professional, concentrating on the guitar instead of glancing around and for some kinds of music, stepping up your 'performance' to give more energy to what people are looking at.