Great fun. Watching I was nervous for you when they got close. A mid air collision would have been terrible. Just a thought: How good it would look if you put both birds on their own Ziplines but parallel to each other, then you could test them slowly and carefully going past each other and then once you know you are safe, fly at each other at speed and the shot would look cool racing at but past each other. Don't forget to allow for a little GPS drift though in your spacing!