what am i doing wrong?

When I ask rio to canter(from the ground) he tends to buck, unless he's already tired. I do know he doesn't like the arena footing(it's muddy and not smooth...fixing it soon) and he has thrown a shoe(farrier coming out in 2 days). He also has been in his stall for a few days because I was out of town and the fields are flooded, so he bucked more than usual. I just wanted to make sure I wasn't doing something wrong, I havn't had lessons in about 10 years. Here is a video

Stop making excuses for your horse. "he doesn't like the footing...." blah.... are you giving solid enough cues.... are you asking for a gait he is not ready for at this point... does he need more flexion, stretching, bending work......... bucking is a lot harder than cantering.... so, what about what you are doing is letting him think he can buck.... a true rider conforms to the horse, not the other way around

I havn't had him very long but according to his previous owner he is well trained and should know this stuff, so I assume it's something i'm doing. Thanks for telling me off, I already knew it was something I was doing...i obviously don't know what it is, so asking me what i'm doing doesn't help.

You arn't doing anything wrong. Do you stop and let him get away with it? Some horses get excited being lunged and mostly at the canter. But if he's doing everytime then just push him forward and keep him cantering. Don't let him get away with it. The worst thing you can do is give up and let him get away with it. Then he will do it everytime and it can lead to bigger problems.
Beautiful horse btw.
Let me know how everything works out.

I do sometimes stop, but I won't anymore. Thanks for the advice :)

My TB does this when I lunge him as well. Usually if he continually bucks into his canter transition, I make him do trot-canter-trot transitions until he settles down. Make him use his brain and think so he doesn't have time to buck! I do these transitions until I get maybe 2 or three NICE transitions out of him...I don't usually lunge for more than 10-15 minutes. Good luck!

It looks to me like you don't have his attention and he is looking at everything around him. When you ask for the canter make sure to have his full attention and have him going at a nice and even trot. He may buck because of being surprised or out of disrespect.
Either way I would work him at the trot for a good amount of time and get his attention on you. Then ask for the canter. If he bucks keep him going for quite a while then bring him back down to a trot. Ask for the canter again and if he bucks again, just keep repeating until you get what you want. Once he calmly goes into the canter let him canter only a few strides and bring him down to a walk and praise him because he has done what you wantedf. Soon he should learn that calmly going into the canter is a lot easier on him because he puts forth less energy.

Not saying this will defiantly work for him but I have done this method under saddle and on the ground for younger horses if they believe bucking gets them out of work. Good luck!

EDIT: Didn't see that you posted almost the same thing Mostbemonroe sorry!

Thanks everyone, i'll try that tomorrow!

He is bucking because he is young, strong and has pent up energy. That's all. It ain't a crime and not to worry too much. He may need some bucking time, so lettig him buck it out during free lunging is cool. Even if he bucks on the lunge line, don't worry too much. Just as soon as is reasonable, ask him back up into canter. The thing that worries me about a horse that is too frisky on the lunge lline is that it's easy to pull them off their balance, especailly if the footing is slick. If he is leaning too hard on the line, then you may want to do one of two things; give it a couple of good snaps to get him to get off of it, OR give him antoher 12 inches of line, kinda suddenlike and it'll put him off balance. He won't like that. Should teach him not to trust the line as something to lean on, but there is a risk that he will loose his balance.

I did see that the horse was not mentally as with you as would be best, but to be honest, he has cabin fever and he's young, I doubt I could get him better focussed on me in that situation.

When doing the leading work, give him a tad bit more warning with your upper body (leaning forward or backward before you actaully move your feet forward or come to a halt. This will help him to be ready. He cannot read your mind, so help him with that Precue of shifting the upper body, then doing the action with feet (yours).
Don't let him get quite so close up on you and he was too far ahead of you, but again, I am not sure I could actually do better at that time.

Watch his eyes and ears to have contstant feedback as to where his though is, and do what you need to get him to give you at least one ear.

He is going to be a stunning riding partner and I sense you two will do well toghether.

As ever Tinyliny gives wonderful advise!