Yag isn't really that long of a wavelength compared to some other lasers, you should be able to see it just fine with any video camera that doesn't have an ir filter in it. I use one of those little cvs disposable cameras with the ir filter removed to see my ir lasers, that is what I used to take the video of the 2w ir laser in my picture to the left. Yag is 1064nm, its about 300nm from the visible red. Co2 lasers are 10600nm, thats 9500nm from the yag! As far as using a night vision scope, I would assume it would work, but I would be worried id kill the night vision scope, It would be interesting to see a co2 laser with an advanced night vision system that can see 10600nm!
i've noticed cheap ir NIGHT VISION GOGGLES in the toy aisles lately. looks like it just uses some ir led's and ir digital camera.
speaking of which, i think DX sells a small digital camera that does ir or something... http://www.dealextreme.com/details.dx/sku.1329 http://www.dealextreme.com/details.dx/sku.15757
possibly could work... maybe adding fog or something would make the ir show up on it.
don't forget the ir goggles haha