I don’t know them all, but I can identify many. I’ll refer to specific times on the video you linked to.
:07 – left ?, center Eddie Dunn, right Stan Ratliff (a.k.a. Brian Champion)
:40 – left Debbie Hooper, right Lucy Crane
1:57 – left ?, right Debbie Hooper
2:08 – Kelly Crane
2:50 – left Johnny Hooper, center Stan Ratliff, right ?
3:20 – Ronny Dawson
3:50 – left Carolyn (later Kershaw), right Lucy Crane
3:36 – Deb Hooper, Stan Ratliff
4:20 – No idea
4:43 – Jim Clancy
Fun to watch. They are obviously lip-syncing to finished mixes for the camera, but they did it convincingly.
Trivia: All of the names I’ve listed have also sung at JAM at one point or another. And Lucy Crane was also the lead singer on PAMS Series 34 (Music Power).