There are a few versions floating around in general circulation these days... There is Creighton Audette's original ladder test, then there is the 'Incremental Load Development Method' from Randolph Constantine which appears to be mostly the same thing, just updated slightly (I think there is an article from Precision Shooting magazine on the subject). Finally, there is the 'Optimal Charge Weight' method by Dan Newberry (goes by 'green788' on a number of forums.
The basic concept of all these methods is the same: finding a 'node' or sweet spot where the the load will be somewhat tolerant of little inconsistencies. The OCW method attempts to address a couple issues, namely barrel heating and fouling that may change between the first shot and the last shot. It almost always takes more loaded rounds to accomplish, but you can often get more useful information from the target @ say, 100yds (if that's all you initially have available) and dial it in further as you need. Also, a lot of people just don't shoot 300yds very well (i.e. well enough to know if one shot goes higher or lower than the last due to the shooter or the load)... I know our ranges here are pretty protected the first 100-150 yards, but by 300yds they are in a jet stream... kind of hard to get good results when your shots are scattered to and fro by the wind!
In the end, any one of these will work as far as getting you closer to a good load. Some amount of final tuning will still be required any which way you go. The video camera method does work, according to others (I always manage to forget to take the dang thing along). Another method that does work reasonably well is to get one of the big 12" Shoot-N-C targets and aim at the center of it (@ 300yds). The bright fluorescent yellow holes against a black background are fairly easy to see under decent conditions w/ even a modest spotting scope (or good rifle scope). Under *good* conditions w/ a good scope, you can often see them @ *600* yards (later testing stages).
FWIW, Dan has a website on his ideas here
, and Randolph Constantine hangs out from time to time over on long-range.com (user name 'lostaxe') so you might be able to PM or email him if you want details on his version.