How did they get such good image quality on something only a few microns in size?

this is on the longer timescale. for nanosecond timescales plants use "non-photochemical quenching" to prevent damage from energetic rays. this is why they look green and not black - they only absorb 90% of the green photons (which are the most abundant)

https://www.quantamagazine.org/why-are-plants-green-to-reduc...

I like the videos on this and how they are presented, very smooth. Something you wouldn't see in a paper magazine.