Dilution and Succussion
Near the start of the video, you see the homeopathic pharmacist preparing a solution from the marigold plant. He puts one drop from the plant solution into a phial containing 99 drops of alcohol and then he succusses it. This results in a homeopathic remedy with a potency of 1c. Then he then takes a new phial, again containing 99 drops of alcohol. He adds one drop from the 1c potency to the second phial and then successes it again. This results in a remedy of 2c potency.
The most common potencies available in health food shops for home use are 6c and 30c. A professional homeopath may use much higher potencies, which have been diluted to a much greater degree.
Highly Safe and Highly Effective
If you chemically test any remedy higher than 12c, you will not find any molecule of the original plant substance present. This is what makes the remedies so safe from any toxic side effects. It's also what makes deniers say that homeopathic remedies have "nothing in them" and that they could only possibly work by placebo effect. Yet, we know from their effect on babies and animals, and from their effect in test tube trials, that homeopathy does indeed work.