When Zack implies that shooting APS-C is a good as Nikon full frame, that doesn't automatically apply to Canon APS-C sensors. We're lagging behind. But when you look at other modern sensors (such as Fuji) that are being put into camera systems in which quality lenses are being specifically designed for APS-C sensors (such as Fuji), you'd be surprised at the high image quality. Modern APS-C sensors are excellent. Rather than being defensive and negative, we should become proactive and demand Canon pick up their game.
A few observations:
1. Whether one is "as good as" another rather depends on what your criteria are - what you photograph, how you view images, how fussy you are about what one should probably refer to as small differences (though that's hardly objective either - differences that matter to me may not even be noticed by you and vice versa), etc. I own several different cameras (too many; I should do some pruning...) - FF (Canon 5DIII & 6D, Sony A7r), APS-C (Canon SL1 & Sony a6000) and M43 (Olympus OMD-EM5), with lenses all over the map, from rather elderly manual Russian lenses to high-end current ones. I'm often tempted to think that even viewing on a 30" monitor, if I don't pixel peep, and don't go out of my way to look for differences, there are many images I've taken with various combinations of equipment which, if I (or anyone else) looked at the images in succession, I would have a hard time matching up accurately with the images, and perhaps a harder time forming a preference.
2. That said, if I do scrutinize, it's not hard to tell the superiority of FF images over APS-C and M43, and not just when comparing Sony/Nikon ff to Canon APS-C. It may be that the a6000 makes better images than the SL1, but it's also true that the a7r makes better images than the a6000, just as the 5DIII and 6D make better images than the SL1.
3. I still don't get all the fuss over Fuji's x APS-C sensors. Before Christmas I bought an XE1 and returned it a couple of weeks later, assuming that the unsharp results, especially in photos where the subject wasn't close, were the result of a defect in the camera or lens, but I don't think they were - I've looked at countless images online taken by fans of these cameras (not to mention the comparisons you can make at dpreview) and seen much the same lack of sharpness. There may be less noise than on images taken with other APS-C bodies, but there's less detail. Frankly, I prefer the images I get from my SL1, extra noise and all. Again, the differences aren't so noticeable if you don't scrutinize closely, and if you care more about noise than detail it won't matter, but if you do.... (Even some Fuji fans acknowledge this - e.g. whatsisname at soundimageplus says they're his favorite cameras to use, but he much prefers the images from his a6000, not to mention a7& a7r.)
4. I've not seen the video yet....