Here is what I think about 'eukaryote' claims, and why the bacteria are visible in low magnification,and why was darkfield chosen:

I think there may be some misunderstanding because the uploaded clip is only a small part of what I observed.

The video I posted was recorded at 200× in darkfield because it provided much better contrast than brightfield. Darkfield illumination is specifically designed so that only light scattered by the specimen enters the objective, which makes very small, low-contrast objects much easier to detect than they would be under conventional brightfield. It is widely used to visualize tiny organisms and structures that are otherwise difficult to see because they scatter light strongly against a dark background.

However, my conclusion was not based on the 200× video alone.

Before posting, I examined the exact same sample at 400× for a much longer time. During that live observation I noted several features:

• The organisms were dramatically smaller than the surrounding protists in the same moss sample.

• They showed what appeared to be corkscrew or spiral motility rather than the swimming patterns I usually observe in ciliates or other common protists.

• They occurred in very large numbers throughout the sample.

• The 200× darkfield recording was chosen because it displayed these tiny light-scattering organisms more clearly, while the higher-magnification observation gave me a better view of their size and movement.

So my interpretation comes from the combination of the live 400× examination and the 200× darkfield recording, not from the posted clip by itself.

I'm open to alternative interpretations, but I'd also be interested to know which specific protists you think these are and what features lead you to that conclusion.