How much data do things use?

I'm thinking of getting an iPhone 5 and I've never had a smartphone before. I would probly get the 2gb, but about how much data do these things use:

Watching a 5 minute video:
Sending a text message
Having a 5 minute phone call
Sending or sharing videos
Taking a picture or video

Phone call - Zero, thats not the data plan.
Any text whether app or msg'ing - Meaningless amount
Video - Streaming… Alot, thats the #1 thing by far.
Taking a picture or video - None, thats not data exchange just taking it.

The bottom line is if you don't watch alot of online video then you won't need a high data plan.