Cherokee Starting problems (with video)

I have heard a few diff ideas about whats wrong with my jeep: spark plugs, NSS, crank position sensor, fuel pump. I posted up a video to see if anyone had any other ideas before I attempt to tackle all of these. It won't make any sounds when I try to start it in park, but neutral it will try but never turn over. It seems to be cold weather affected bc it only started when the temps finally started to drop here in GA. I just shot this vid on my iphone so not the best quality, let me know what you think! Thanks!

http://www.youtube.com/watch?v=s_RTH04cZA4

Oh and it's a 2000 4.0

Watched your video. You have more than one thing going on.

Problem #1. Neutral safety switch. The fact that it turns over when you put it in neutral confirms that. You might be able to restore function by trying this....

http://go.jeep-xj.info/HowtoNSSrebuild.htm

Problem #2. Your battery sounds weak and the engine isn't catching. Start with load testing your battery at a parts store (free). Then with a good battery, try again. The engine management doesn't like it when available battery voltage is low.

sounds like the starter bendex is not staying engauged too. After you get battery charged or replaced if the starter still kicks out when cranking it rebuild it or replace it and a good tune up will help alot from the sound of it . If your engine is running right after it worm you should just have to bump the engine to start it mine turn over twice and starts .

I concur, 1) NSS needs cleaning 2) crank rpm is too slow and its not getting a good crank signal so charge/check the battery and check the cables/grounds.