Jennifer Crank says:

His backing up looks great. I don’t see anything to worry about. Even the few he went crooked and not onto the mat didn’t bother me. You could have him do it parallel to the wall instead of into the wall if you want to work on him being straighter but I’m not super picky about that. This isn’t really an agility skill. It is just for shaping and body awareness so we can be more lax about it compared to some things, like perch work.

You can work on increasing the distance he backs up over time if you’d like. I will admit that none of my dogs have a really huge distance on backing up. I’d be more inclined to start adding behaviors at the end. Can he back up and then sit or down?

The biggest thing that drew my attention on this was the markers, or lack there of. I didn’t hear anything consistent when he made it to the mat and I didn’t hear anything when you set the cookie back in from of you to reset him. We need to get the cleaned up ASAP.