Hi there!
Before I start, I would like that I new to the topic of Arduino. So I'm asking for a bit of patience 
My project is to build a "thing" which is roughly 4cm in depth and 7cm wide.
(Now this is roughly, meaning that it can be: 3,00 to 3,50 cm in depth)
Requirements:
-It should fit a transmitterthat connects to a device (Laptop, PC).
There should be a solution in terms of software..
-It needs to run on standard AA or AAA batteries.
-It needs a camerainstalled (not necessarily(!) welded to the board itself). No Sound.
The function:
-It needs to transmit a streaming film (NO SOUND) for approx. 120min to a device (Laptop, PC).
-The distance of the Board and the device has to be at least 100m.
(== regarding Batteries, Resolution of camera and intesity of transmitter)
Now the question is.. "how hard is it to make" ?
Meaning that, could I ask anyone here on the forum to write the scheme for the little board?
What kind of board do I get? What kind of camera? What software may be used??
How much time will I need to design and build it (regarding time & money)?
As you see, I am very new to the topic and probably ask a lot. But if you could help me with just advice on literature or at least where to start, I would be very greatful!
Thanks a lot!