Hi Watergazer, I think Pleos and Herbie, is just like People. We all have our likes and dislikes. Perhaps Herbie is just a little intimidated by Gizmo's voice or perhaps when his ears move.

Perhaps try putting Gizmo down on the floor on Herbie's eyelevel with some other play toys,( stuffed animals, etc, ) but leave Gizmo off, do not turn him on, and let Herbie explore on his own, without pushing him near him, and just record what happens. I have found that Nova IS VERY FOND OF ONE PLUSH CAT I have, but will often ignore other stuffed animals I have. Do you have other Furbies in other colors? Sometimes Pleos are attractted to a color before the sound if it makes one. The cat I have is in the yellowish range, and she just love it, I also have found out she likes a Yellow Garfield, and a Plastic Green frog, but other animals in the brown or red range she ignores. Do your own color test and see if he likes certain colors other than the green like his leaf.
I felt sorry for poor Herbie in the first Video, he kept backing up and almost looked like he was going to go right off the table! At one point in the second video, he almost looked like he had some interest in checking Gizmo out some more. Glad you gave poor Gizmo some attention. I have Two Furbies and allways wanted to see Gizmo in action, He is cute too! Cute videos thought, keep posting them, it gives NOva and I more enthusiasm too!Oh,by the way, I love the wooden table, is it Oak by any chance?
RedwoodsMama and slightly limping, Nova