They're probably using some type of fast lossless or nearly lossless 'compression' that cuts the really low hanging fruit out but doesn't extract quality they care about.
HuffYUV, for example, if you're going to be targeting a 4:2:0 output stream; if you're going for 4:2:2 or even 4:4:4 for some super HD stuff you might use different options.
HuffYUV, for example, if you're going to be targeting a 4:2:0 output stream; if you're going for 4:2:2 or even 4:4:4 for some super HD stuff you might use different options.