One of the 4 ingredients in the spiritual purification is scarlet. The exact wording in the Torah is “scarlet [from a] worm.” Rashi explains that the worm (like the hyssop) comes to rectify the high uplifted and arrogant spirit of the leper – qualities that caused him to becomes diseased in the first place. According to Rashi, this is the only aspect that is rectified by the service, whereas in the video we mentioned other commentaries that discuss the birds being a rectification of speech.
In any case, even though the Torah states that the scarlet should come from a worm, as Rashi states in order to symbolize lowliness, the sages (Yerushalmi Kilayim 9:1) learn [apparently from the order of the noun and adjective, shni (red of the) tola’at (worm), rather than tola’at (worm of) shani, as it appears in the description of the priesthood clothing–see Pnei Moshe on the Yerushalmi there] that the scarlet does not have to come from a worm, but rather from anything that is a living animal. There is quite a bit of learning surrounding this issue, but what we would like to get at hear is the division of the 4 ingredients into animal and plant life. The birds and the worm represent the animal kingdom and the wood from the Cedar tree and the hyssop represent the vegetable kingdom. That the two birds go together with the worm under the same heading could be another source for the sages’ teaching that it doesn’t actually have to be a worm, but rather any animal that is alive, i.e., in their exact wording, that has the breath of life in it, because the main thing about the birds is that they be “alive,” and their breath is the very chirping that we mentioned that rectifies the power of speech.
Now, the worm is usually described as a creature that takes resources in, but has no excrement. This special trait, when transferred to holiness, symbolizes the ability to be a person who can hold secrets, i.e., not to gabble. The worm’s strength is in its “mouth” and from that we learn that we too, the main focus of our power is in our mouth, in Torah study and in prayer.
Another interesting point that we have not seen mentioned in other sources is that the word for “scarlet” here, shni (שני) can be read as “two” (pronounced: shnei), providing another connection and parallel with the “two birds.”