The armatus is way bigger then that peacock bass. In the video you can see some big ones in the tank along with the armatus. I would say that if the peacock bass is quite a bit larger then the armatus, go for it. Anyways you will never know until you try and i am just offering a suggestion. And its always to have lived and tryed than to have died and never known.
Do consider the personal temperment of your two fish first though. Such as if the payara is peacefull and the peacock bass is a little aggressive, thats a lot better than if you have an aggressive armatus and peaceful peacock.
Thats what makes this hobby so interesting and awesome, please do keep us posted and let us know how it goes if... You go for it.