The 4:2:0 relates to the amount of information contained in the shot. The 50D is a 14bit 444 image at a resolution near 1600x900. If you blow up the image you have a near 4K 4:2:0 native equivalent. More importantly, it's probably closer to a 10 bit 4:2:0 luminance/chrominance than an 8bit.
*** Most of the latest camcorder and DSLR gear will shot a native 8-bit 4K 4:2:0. It will have a sharp picture but will fall apart in the gradients. What that means for 50D shooters is that you are capturing footage with a softer, yet smoother transitioning image. An image that can be more cinematic in nature than the 8bit 4:2:0 4K that down samples to 10bit 4:4:4 Full-HD native equivalent. Apples to apples, the 50D is more than likely capturing the equivalent of a 12bit 4:4:4 Full-HD image/data equivalent even though it is a native 1600x900.
*** In a recent test, I was able to get a sharper image with a 50D / VAF combination than the Full-HD BM Pocket Cinema Camera. The Pocket Cinema was falling apart in the moire department and couldn't withstand the same up convert process as well as the 50D with the VAF. Apples to Apples, the Pocket Cinema was shooting a native 12bit 4:4:4 Full-HD image.
Obviously you can't change the sensor, but you can capture every last bit of information that the sensor has to offer. The freedom that this provides truly allows for a multigenerational capture acquisition... The type of camera that is now nearly 6 - 7 years old and still has a place at the frontline of prosumer equipment. In essence, it's a very powerful statement and a wise investment for image capture acquisition. Maybe the best?