With 2014 jumps to date and nearly 1000 of those being camera-jumps, I can assure you skydivers can indeed look down but few do because they are intent on performing complex aerial manoeuvres with others (relative work), or sit-flying, or freestyle where a reference to the horizon is required at all times. Mostly they are looking horizontally, focussed on other skydivers at distances between three and fifty feet in most cases.
As a cameraman I was intent on my target and had extremely limited visibility under the camera-helmet anyway. Almost all my freefall time was spent looking through a ring-sight at a target horizontally in front of me (a lot of tandem jumps). However, as my footage shows, after disengaging from the target I always looked down to find the DZ before opening.
On one such occasion I looked straight down at a Cherookee Archer which was overflying the DZ not all thatfar below me. I didn't have time to make a note of his registration for the incident report but I did the next-best thing...I took a photograph of him which also showed his position relative to the DZ. "Evidence In Camera".
I left it to the DZ operator to take whatever follow-up action he felt appropriate. I never saw the photograph. This particular DZ has been a danger area on the air nav charts since 1970 and still the "I follow Roads" crowd persist in flying straight through the airspace at parachute-opening height. It is solely used for skydiving, not shared with powered aircraft or sailplane operations.
It's only a matter of time...