Great stuff, I often see video's where they say it's 20+ knot winds but it always looks flat, that showed it was the sort of stuff I always get in 20 knots and love it. When I first started to sail the AI I used to let my sail luff when reefing but now I try to keep a bit more tension on both lines to help stop it from flapping, works quite good and has to give the sail some extra life. With the tandem being so long and the extra drag on the lines it may not be possible but worth the try I would say.
A lot of people say dry-suits are over kill, to expensive, etc etc but once you have one, it will be the first thing you go for almost every time due to there comfort and ease of use, keep a bit of a log, temp, conditions etc and what undergarments you wore it help you learn/decide on the day as to what to wear until you become good at judging what will make you more comfortable on the day without having to undo it to remove layers.
What brand did you get and did you get relief zips or valves, valves are very good for the ladies used along with a she-p http://www.she-p.com/
(not shepee,org, its slightly different and does not have the seal) for comfort on the run, the valves are expensive but like the suit, once you have it, there is no looking back. As for the guys, if it's just for use on the kayak then the zip is probably cheaper and easier, if you also dive in it them I would get a valve as well.
Anyway, great Video once again and get out there, luv-it.