I could not get the video to run.
However, I've seen worms at high densities show weird behaviors not seen at lower densities.
This is really apparent with small worms, like C. elegans, that are about 1 mm long and about .1 mm (100 µm) or less wide.
You can grow and concentrate them to high densities.
They can be very active, squirming around rapidly.
They also seem to stick together, maybe by surface tension of their tiny wet surfaces in a non-liquid environment.
When they are packed side by side, they can move around as kind of banana shaped bunches of worms, which can squirm along the surface. At times they can even lift off into the air like a tentacle.
I have seen high densities of collected (almost microscopic) worms do this.
- are very thin compared to their length
- are pointy at both ends and otherwise undistinguished head and tail
- move by extending and contracting - like an earthworm, only more pronounced
- are oxblood-red.
These critters seem to have a bulbous and distinctly white head, as well as being fairly thick. They also do not seem to extend/contract much as they move - more akin to caterpillars than worms.