There is no 32G option.
Since you mention that you will use it to take short video, which make perfect sense, because the 6+ comes with a very nice camera. However if you take 1080P 60FPS video, which will easily take up 1GB for a video that just few minutes long.
Also, the modern apps is getting bigger and bigger. Lightroom ~1G, iMovie ~700MB, Keynote + Pages + Numbers ~1.2G.
IMO, get at least the 64G model, otherwise, you may not even able to take good quality video for 30min. If you prefer to lower the video quality, then why you need the 6+? Just for the bigger screen?
I have a 6+ and I am not a heavy iPhone user, ~140 apps+ ~1000 photos + 24 short videos (average 1min long). I backup all the large video, and clean up my iPhone almost every night. It still takes up 16.8GB now (including the iOS itself). So, my suggestion is don't go for the 16G model. Even though you never use any powerful apps, you may still very tight on the storage (~2G buffer? May not enough for OTA), and no way to take any good long video on an important memorable occasion (Or few short videos and then choose the best one later on).