For anybody interested in videoing what's going on under and around their aircraft in flight, I suggest helmet mounted cameras fit the bill perfectly.  In particular, i temporarily mounted a 4oz, fully self-contained & weather-resistant, video camera to my rear tie-down ring socket to see what my landing gear is doing.

The camera can be had for less than $300, and is the ContourHD from www.vholdr.com

Sample video (mine) is at http://www.youtube.com/watch?v=sShijby0JQU

Should be great to see what gear doors are doing, for instance.