The question is, does the little girl understand the meaning of drinking from a penis? Can she in fact, even in principle be capable of understanding what it means? If NOT, then one cannot say that she can be used to portray this kind of freedom of speech. She is being abused in the making of this video. He rights are being trampled to portray something. In this case her rights are more important then the satire the sketch aimed to portray.
Context is always important. Child porn is not freedom of speech because we believe that little children can’t consent to sexual behaviour, because they don’t fully understand it and it’s harmful to them.
Seems to me that there is an anti-Japanese angle to this. While Japan has a problem with child pornography, most Japanese parents would not do this to their child. And yes there are penis festivals, but they involve grown up women, not babies.