How much 'VRAM' in Pro vs. Air?

The VRAM depends on the GPU: if it's dedicated or integrated and the GPU itself. If it's dedicated (the NVIDIA GPU of the 15-inch MacBook Pro), the VRAM is always the same and can't be upgradeable.

However, all MacBooks Air and MacBooks Pro have got an integrated GPU that has got a VRAM size depending on the amount of RAM they have and the GPU itself. See > http://support.apple.com/kb/ht3246

At this moment, all new MacBooks meet the Final Cut requirements. If you want to use Final Cut, I recommend you to get a 15-inch MacBook Pro, because it has got a dedicated GPU that will work much better with Final Cut instead of an integrated GPU like the ones that the MacBook Air and the 13-inch MacBook Pro have got

Jason Fredregill wrote:

Apple states VRAM requirements for Final Cut but I am unable to determine what machines have what amount of VRAM.

For the Pro line, the product pages do tell you how much VRAM they have.

For the Air line, the Apple tech note that mende1 posted does tell you how much VRAM is available for a given amount of system RAM installed on those machines.