It seems that the "joke" is that the director had the kids actually say "f#%@" and "f#%@en" [English: f$%#, to f$%#] instead of "freiheit" [freedom], and then censored all the  f#%@s to make it look like "freiheit" was censored.
 
I guess it makes sense to Euroweenies.

The clip also presents authoritative principles on the screen, as the static property of the scene itself, i.e. of the EC, contrasted with the confused, emotional, uninformed, imitative jabberings of the human subjects, who are children. It implies that the subjects of the EC are as children, and that the possession and definition of the high principles of government belong to the government. There is no exchange between the subjects and the government; the subjects merely chatter at each other, or remain silent. Either way, they have no effect on the government.

In other words, the principles are proffered as sacred symbols that pertain to the sacredness of the EC; the words of the children are insignificant in comparison.

The little puppets are censored, yet express themselves in opposition to censorship. They are both free and not free. The piece seems to demonstrate the intention of European government to control both sides of any political discussion: it will vet the terms of the debate both for and against X, both for and against Y. Z will be silenced. It wants to present itself as impartial, but its impartiality is limited by its own determination of the acceptability of the propositions offered by disputants.

The abuse of Beethoven echoes Clockwork Orange.