I have a Nikon D5100 should trade it for a Canon T2I?

I have a Nikon D5100 should trade it for a Canon T2I, I'm a cinematographer and i believe that Canon has a better lens collection & more accessories & compatibility for videography so witch do you think?

Have you actually compared the lenses that each company provides. I think you'll find both companies have an impressive selection of lenses. With Nikon, you can use lenses going back 50 years, Canon goes back to the late 1980s for the EF mount. If you already have serious glass for your D5100, then switching systems could end up being very expensive.

Since you're only interested in serious video, you can use Nikon's AF lenses since you will be manually focusing.AF lenses won't auto focus on the D5100. Ken Rockwell has a nice listing of Nikon glass:
http://www.kenrockwell.com/...nikkor.htm

Most accessories for shooting video are camera manufacturer independent. Lights, dollys, tripods with fluid heads, steady cam harnesses, LCD loupes, remote microphones, audio mixers, separate audio recorders, … Will work with any camera, including real camcorders. Remote monitors, you'll need to research that one which could be the deal maker. The D7000 works fine using a remote monitor via the HDMI connector. The D5100 has an HDMI connector, so I assume it will work similar to the D7000.

Frame rate could also be another interesting item if you need to shoot at 60fps. Again, you need to research this.

You aren't a cinematographer, you're a guy with a camera, just like about a million other guys with cameras.

All three of your beliefs are wrong. Switching systems will not make a bit of difference in your results. But hey, it's your money, waste it as you will.

Only if you're really stupid - Sony do better video than either.

Anyone with any sense researches and then handles possible candidates before choosing the camera they want. There's nothing that Canon can do that Nikon (or anyone else) can't.