It's simply too expensive for a *kit lens*.
Canon has something similar for way less.
Nikon should instead concentrate on coming out with a 24-70 f/2 VR
Better start investing on getting that else they'll lag behind.

Just a personal opinion,
Canon handles video a whole lot better than Nikon.
+ Can change aperture and audio levels while filming
+ Magic Lantern
+ Most canon has better video frame rate of 30fps at 1080p while only the latest/newer Nikon can do that.
+ I prefer canon white balance since some Nikon models have a slight green tint. Video colour correction is harder to do than stills.

That being said, I fine shooting stills better on the Nikon due to the AF and exposure metering. (For budget DSLR of a similar level, a 70D will be better than a D3100 of course)

Just my 2 cents from owning a dual system setup.

For photos, it's not a need.
For videos, it's probably advisable to get at least class 10.

It's not that much more expensive, go for the class 10.

Don't think so much about memory card.
It's quite cheap comparatively.

Even an Extreme Sandisk 16GB class 10 45 MB/s (aka a pretty good card, if class can go beyond class 10, this will be a class 45 card) SD card would cost about RM 100
A regular class 4 16GB card would cost about RM 50.