Exporting for web from After Effects using Media Encoder

There is no such thing as CMYK video. The issues you are seeing are similar, though. You overcranked the colors and the color range for MP4 videos cannot accommodate . Similarly, the videos will always soften a bit due to how this compression works and very thin lines like in your "up" text can be eaten away by the block artifacts. This has nothing to do with AE, it's normal behavior for MPEG-based files. It can't be fixed with magical technical trickery or any of that. That being the case, you'll have to work on the design to be compliant with those limitations like toning the greens down to fall within the color ranges. A simple Hue/ Saturation to reduce the lightness and saturation by around 3% already can improve things quite a bit. Using actual color management might also help. There's no simple "Do this, do that!" here, though. We all had to learn this and accumulate experience, which is the crux of the whole thing.

Mylenium