By the time we video taped Cosmo, he resumed walking normally.
He is back to using his brace most of the day. He is walking on all 4 legs with the brace.
I am going to try to include the video.

I emailed Orthopets about what was going on with Cosmo.
They called me and they want me to send them a video of Cosmo walking with the brace. They want to make sure the brace is fitted correctly. I will have to get Addison to do it. LOL. I have never video taped anything.
Cosmo is resting on his bed today with a big juicy marrow bone. He is still limping and seems willing to simply rest today.
We may put off video taping until Friday.

I feel like the brace caused an oops moment but I just do not know for sure.
Cosmo is limping today. We have removed the brace and are limiting Cosmo's activity. We plan on reintroducing the brace with the beginning schedule (2 hours at a time) in a few days. I do think that having Cosmo swim without the brace is the way to go. It allows him more movement of the leg. In a couple days, we will allow him back in the pool, minus the brace.
I want to believe that the brace is protecting the leg while it heals. I just am unclear why he started walking off kilter and what caused him to fall yesterday. Without any answers coming from Cosmo, we will just keep plodding along and making adjustments as we go

Well, I have been happy with the Ortho brace. Now, I am not sure. The past couple days, Cosmo seems to be walking off kilter in it. We kept him off it for awhile and he seemed fine. It isn't wearing funny or rubbing wrong. Today he fell with it on. He is currently resting on his bed. I don't know, maybe it is not the brace. Maybe he is overdoing it. I just wish the dog could talk and tell me what he feels. I was confident that we were progressing nicely. Now, I am thinking we are suffering a set back.

Cosmo is doing great! The brace was well worth the expense! I highly recommend the brace.