Benzene (C6H6) is the most basic type of aromatic hydrocarbon. Some field specialists may call it "benzol" instead, with a more German flavour.
"Benzine" and "benzene" are homophones, but they represent completely different substances.
As a functional group, benzene is called a "phenyl group". Phenyl groups are usually abbreviated as "Ph". An aromatic hydrocarbon functional group is called an "aryl group", both the phenyl group and the naphthalene group belong to the aryl group.
In benzene, six carbon atoms are arranged in a tortoise shell shape (hexagon), and each carbon takes on sp2 hybridization for its electron orbitals. In resonance, benzene's carbon atoms appear to alternate between double and single bonds, but in reality, the π electrons are delocalized and do not belong to any specific bond.
Moreover, all bonds in a benzene molecule are equivalent and do not vary according to resonance. To emphasise the delocalization of the electrons, it's often to draw a benzene ring as a hexagon with a circle enclosed inside.
Benzene is a basic substance in the chemical industry represented by petrochemistry, and the following four chemicals, similar in structure and properties, benzene, toluene, ethylbenzene, and xylene, are often called by their initial letters "BTEX".
..is what they say, but this explanation has absolutely nothing to do with this video. Now then, shall we move on to the actual song?
The song started with an explanation on "Benzene" (C6H6). It explains the forms of Benzenes, how they are formed, the chemicals, and also other examples of chemicals which are similar to Benzene "toluene, ethylbenzene, and xylene". Do they have anything to do with the series? Toluene turns out to be the fifth song to it. Though by the end of the explanation, the long explanation had nothing to do with the video.
“Now then, shall we move on to the actual song?”
As commented by both Paradichlorobenzene and Antichlorobenzene, "the two songs" (which may refer to Benzene and Nitrobenzene) has no meaning. Though Toluene said that there may be a meaning to it. Nonetheless, at first sight, it doesn't seem like there's a meaning to the song at all.
After the explanation as well as at the end, "Han'nyara youjo!!" is sung, which means "Prajnaparamita little girl!!" Prajnaparamita is made of the two words, prajñā "wisdom" and pāramitā "perfection, thus in English making it "Perfection of
Transcendent Wisdom". It is a view of a perfect seeing reality, within Buddhism. "Zun dara mochi, iso gin chaku, benzene. ヽ(゜゜)ノ Benzene! ♪ " (which means "Rice cake (mochi), sea anemones, benzene. ヽ(゜゜)ノ Benzene!♪") is repeated throughout the song, with the only valid sentences saying "there is no meaning to this verse". "Therapeutic" is a medical side effect, which is good for said patient. In this case, it may mean that "brainwashing" had a "good" or beneficial side effect. This likely applies to the other brainwashing songs.
One of the video's tags on Niconico Video said: "the people who laugh from Paradichlorobenzene and Antichlorobenzene". In both songs it's written there are those who "laugh", this song, Benzene, may be the song the "people" laugh at. In Niconico Video, many "hahaha / LOL / wwww" comments are posted in Benzene. In fact, the amount of comments are far, far, greater in amount than the mylist (30,000 comments with only 6,000 mylist).