the basics - you can mount Nikon glass on Canon with rather cheep adapter, because the Nikon's F-mount flange to focal plane distance is 46.5 mm, but Canon's EF flange focal distance of 44.0 mm and diameter is bigger so there is space for an adapter without any use of additional optics.
but, there are things to consider - Nikon's F mount has many variations (not like Canon's EF), for example mechanical drive for focus vs. electronically, manual and automatic iris control and so on.
I do not know any active adapter, this no electronic control of a lens is possible, thus for example G type Nikon lens (lenses without an aperture ring) there is no way to control the iris, thus rather pointless for video.
much of info you can find in thees two articles:
http://en.wikipedia.org/wiki/Nikon_F-mounthttp://en.wikipedia.org/wiki/Canon_EF_lens_mountCrop factor depends on the camera sensor, not the lens. Canon's APS-C is 1.6 crop, Nikon's crop sensor is little bigger 1.52 (
http://en.wikipedia.org/wiki/APS-C). There are lenses that are meant to be used on crop sensor cameras and can not be mounted on full frame ones there for there is canon EF and EF-s (crop sensor), and Nikon's FX and DX respectively. Keep this in mind - tough most of the primes are meant to cover full frame.
As I understand you want lenses for video - there are many much easier options in m42 mount world form manual film camera days. m42 easily mounts on canon's ef, most of thees lenses have rather long turn from one focus point to other, and the best trait - they are cheep, yet surprisingly good. I have some notes about soviet made lenses I use in my video work here:
http://ansius.lv/old-m42-lenses/ (sorry the web page is slow at the moment, I have some hosting problems)
for the price of one modern nikon lens you can get good 2-3 primes, so do some research and keep asking questions. I have spent some time researching lenses and there is a solution I'm really interested - pentacon six medium format lens on canon ef with a tilt/shift adapter in between., saving money for that
