There's no inherent advantage to either band, except 2.4 GHz antenna can provide more gain per size. Both 900 MHz and 2.4 Ghz are unlicensed bands (at least, in North America). Once upon a time, the 900 MHz band was used for wireless headphones and speakers, cordless telephone and baby monitors, but these consumer products have mostly fallen out of use. These days, the 2.4 GHz is heavily used by WiFi. Which band has less interference depends on your local circumstances. 900 MHz equipment is more likely to be manually tuned.

If it was me, I'd get a WiFi version of the camera (not just 2.4 GHz, but specifically Wifi enabled). They're not that much more expensive.

 

The main benefit you might see with the 900Mhz camera is incresed distance over the 2400MHz camera.

The 2400MHz camera might have better video quality given the higher bandwidth avaialble of the band.

I guess it comes down to what you need, longer distance or greater flexability.

2.4 GHZ
Smaller antenna, more bandwidth. More likely the modulation method is digital due to more modern chips being available and due to fact that 2.4 GHz is a recognized band worldwide (i.e. manufacturers will invest more in doing a chipset right) Digital modulation gives better reception and more immunity to other devices in the same band. Little less range at the higher frequency. The band is getting a somewhat crowded with other devices.

900MHz
The band is not as wide, so bandwidth of a design may be reduced. This band is primarily North America only (the 868 ISM band of Europe is too narrow to support video). Slightly less attenuation at this frequency, so more distance for the same transmitted power.

When you speak of the amount of bandwidth available in a particular frequency range, do you mean the amount of bandwidth that you're allowed by the governing body for each particular device using that band?

I guess that would be the same thing as the size of a channel?

If this is correct, then how would you go about figure out the available bandwidth at each region? I looked at the FCC Table of Frequency Allocations, and wasn't sure how to get the information.


 

You have to look up the applicable regulations.

E.g. "Part 15" for the USA: http://en.wikipedia.org/wiki/Title_47_CFR_Part_15

(The above Wiki link is intended to help you get started. Obviously one would not rely upon the information on Wikipedia except as a useful and easy starting point.)