I wouldn't sweat it bro, and instead of learning how to do a flying armbar, learn how to defend it so next time you get in there and they do one you push them back and they fall on their head.
It's a flashy move and easy to defend if you know what you are doing. I have had guys try it on me before and they usually end up landing on their head. I did get caught one time though...guy came talk to me before our match and he told me it was his first match of the day so he was gonna start out slow and pull guard...I believed him, stupid me. He pulled a flying armbar 5 seconds in and sunk it before I knew what happened. He pulled my shoulder out of socket which luckily gave me enough to get out. I then proceeded to destroy him. I made sure that I didn't tap him until I heard the ref call "1 minute"...moved to side, secured kimura, looked down and said "you gonna tap or you gonna make me torque it?". He tapped.