TL;DW:
Due to various molecular configurations (aka polymorphs), currently known medicines when contaminated with a catalyst seed molecule/particle can become irreversibly unreproducible via chained-contaminations.
- the contamination can cause the existing configurations to become more stable in a negative fashion where the medicine/compounds no longer work they way we expect them to.
This system of contamination and reproduction acts in similar fashion to viral infections.
Current Solutions:
- better clean room procedures for all steps of medicine manufacturing.
- pour more money into medicine polymorph research.
Yes, it's gallium corroding aluminum or something like it, but the video is about pharmaceuticals.
It's just a visual analogy. Once aluminum is infiltrated by the gallium it can't be reverted, only removed/replaced.
Not only visual, it's the exact same thing: polymorphism. It's therefore an extremely relevant and fitting thumbnail, and chuckleslord is a fool for assuming otherwise without giving the video a shot.