I've made a few videos in the RV-9A as I've been developing various exercises, measuring parameters... and I've done a ton of analysis on recorded G3X data over the last few years. The bottom line is that video for flight test data capture records impressions and commentary but has almost no value for quantitative data, certainly in comparison to the data recorded on the SD card.
* Most important I think are good test cards, with *everything* you need to set properly to hit your test point. If you don't hit your test point, the recorded data has no value. Ask me how I know about needing *everything* you want for a data point...
* Get familiar with the G3X data format as you won't have to record all the data manually. However, some of the data, especially AOA and vertical acceleration (g) are noisy, so you won't necessarily be able to take individual recorded values without a grain of salt. I'll be happy to send you a flight or two (.csv) for you to play with if you send me a PM;
* External view videos, at least for flight test data capture, are pretty much a so what. Nice for posting, of little value for analysis, lots of searching to find what you want. And if you do have an external view, make sure that you have some reference video to check it against;
* You might want to set a camera to capture your button pushes on the G3X, GTN, whatever you've got. There's a goodly learning curve there, and sometimes I at least can't remember what buttons I pushed when;
* It's too bad that the FAA doesn't give letters of authorization to teach avionics, as the combination of unfamiliar airplane and unfamiliar avionics can create excessive workload for a first flight;
* You might consider just audio capture, especially something that doesn't record silence. I've not tried that myself, so I'm speculating;
* When I've video recorded maneuvers, the video was good at capturing comments and ideas. In the -9A, things like stall buffet and even some stall breaks weren't all the visible on the recording, so the play by play commentary was where 90% of the information was.
In other circumstances, I'd invite you to Savannah to play with the G3X with me, discuss configurations, etc. Hopefully there's somebody local who can guide you through the initial stages and get you proficiency up to a reasonable level before first flight.
Speaking of first flight, in advance, congratulations!
Ed
PS. Make sure you work with an EAA Flight Advisor. I'm one, even if far away...