New evidence on the seizure that rules out the three members of SeeYa's claim.
SeeYa's claim was that they did not see her fall. As you can clearly see, the members make eye-contact with the dancer, as well as each other.

Everyone on the stage saw her, besides Nam Gyuri, engrossed in her own lip syncing. One back-up dancer in particular is traumatized by this.

(I didn't make this I'm just re-posting to show the new angles sorry to original poster) (less info)