Canon T3i + Nikkor lenses?

I just bought a Canon T3i, which I intend to use mostly for video.
I have a few nikkor lenses, that I've mounted on the camera with a fotodiox adapter (the cheaper kind).
They are all G-type lenses, so I ran into a problem with aperture from the start. My biggest problem is that when I turn to the video preset, there's an error that says "Ensure a lens is attached". If I press it again, it let's me shoot the video but only for about 9 seconds, and then it stops automatically.

I have a SanDisk 16GB, class 4 memory card.
I'm pretty new at this, so it might be something obvious?

Added (1). Again, it's not important why I have the camera, that isn't going to help anyone. I actually have a Nikon D90, and it supports video as well.So, the concern isn't in why I didn't get another Nikon.

I have to wonder why you did not just buy a Nikon D3200 and use its video with your lenses.

Is the hype about Canon dSLR cameras video that invasive in the culture of using dSLR's to shoot video?

Unless the adapter you have has electronic contacts, there's no way for the Nikkor lenses to communicate with the T3i. It is important that the lens aperture setting can be "read" by the camera to assure a proper exposure.

So you have a Nikon D90 and a few Nikkor "G" lenses that don't have an aperture ring on the lens and you buy a Canon T3i? What were you thinking? Did you really think an adapter would magically make the Nikkor lenses work on the Canon? I really can't understand why you didn't just buy a Nikon D7000 body. Sell the T3i and buy a D7000 body.

The adapter doesn't allow the lens to connect electronically to your camera, so it won't detect the lens or allow you to change the aperture electronically (since they're G lenses, you won't be able to change the aperture at all).

As for the video not recording for long, that's probably just due to the memory card being too slow. Try using a class 10 one.