I've tried a number of things for mounting a video (or still) camera on a wing-tip over the years. It's more difficult on modern gliders, as most everything is enclosed. You have the cross-bar junction (where the cables emerge from the sail, and the wing-tips (if you don't have the Sensor-style tensioned tips). Besides the difficulty of finding something to attach to, I also wanted it to be easy, as otherwise I would never get around to attaching the camera. So, the first step was to create easy attachment points. I did this by drilling into the plastic plugs in the ends of the wingtips, and permanently fastening an L-shaped bracket:

My first attempt at a video cam was with a Mini-DV camcorder, which weighted a couple of pounds. Here is the bracket I made to hold the camera and attach to the wing-tip mounts. There is a single bolt into the base of the camera, which allows rotation in the horizontal plane. The slotted hole in the tip mount allows up/down angle adjustment, so it can be easily aimed when attached. Because this was an expensive piece of gear on a hang glider wing-tip, I added a protective bracket to the bottom of the mount - it will hit before the camera does.

You may have noticed I said it weighed a couple of pounds. That much weight was too far out (16 feet?) to leave unbalanced,
so I made a set of balance weights to go on the opposite tip (an idential tip-mount had been installed there too).

I was never very happy with this setup (still slow to attach, lots of added weight, and trim problems), so I did not use
it very often. The only videos I made with it that I've posted are Thrust Turns and
Flight Operations, both posted in the
Video Gallery
After those efforts a few years ago the whole set-up has mostly been put away in a box.
I had been looking into the "Helmet Cams" being sold, but most were low resolution, and I thought maybe something better would eventually turn up. I was right, and this spring (2009) I discovered the Contour HD High Definition Helmet Cam. I had to wait over a month to get it, but this 5-oz camera (10 oz including the aluminum mounting bracket) was the answer I had been seeking. I simply used my old video camera mount bracket, and stuck on one of the several camera mount options for this camera (peel and stick adhesive). The mount itself has a sort of velcro attachment, so the mount can be separated and rotated to a new position.

Best of all, it takes excellent videos, as seen in these clips from a FlyIn at Hyner View Pennsylvania in July 2009.
In the clip above, there is also a keel-mounted point of view. That was achieved using the same mounting hardware and lots of Duct Tape:

(updated July 11, 2009)