@JackRacc Okay, so the problem is unrelated to the captcha. Because HD720 was removed by Youtube, we changed the default quality to "DASH", which is not supported by the current version of our player (VideoJS 7) on iOS.
We're planning to update VideoJS to the next major version (8), but until then, all you can do is select the "medium" quality in the preferences.
-SamantazFox