Movies 1 and 2 show the ciliate Woodruffia ingesting Phormidium autumnalae filaments. Movie 3 illustrates that filaments covered by a sheath became unavailable for ciliates. The twisted filament noticeable in the Movie 4 is much more resistant than the solitary trichome visible in the right side of the frame.
More information about ability of cyanobacteria to defend themselves against ciliate grazers is available in these papers:
Agnieszka Pajdak-Stos, Edyta Fialkowska, Janusz Fyda, Phormidium autumnalae (Cyanobacteria) defense against three ciliate grazer species, Aquatic Microbial Ecology, 2001, Vol. 23: 237-244.
Edyta Fialkowska, Agnieszka Pajdak-Stos, Dependence of cyanobacteria defense mode on grazer pressure, Aquatic Microbial Ecology, 2002, Vol. 27: 149-157.