This polymer antibiotic sounds very interesting. I would imagine it would first get used in surface antimicrobials due to ease of approval. Although perhaps that is a bad idea, as perhaps a new drug classification should be well protected to prevent the evolution of microbial resistance (if that is possible).
The film indicates that the bacteria and human cells have different static charges. Human cells actively pump potassium inside and sodium outside, with a somewhat higher concentration of sodium outside than inside. Anyway, so the cells have a slight negative charge inside, and positive charge outside.
Here is from the film clip.
So, I would interpret that the polymer attacks cells with internal negative charges... which sounds bad. But, perhaps this is mistaken.
This also would have little impact on intracellular bacteria.
I would worry that the polymer could lyse neurons that are active with action potentials. Or cardiac cells? Also, look for impacts on the kidneys and liver.
Anyway, it is always a long route from in-vitro testing to animal in-vivo testing to primate testing to human trials, but it sounds like a very promising drug.