The developer need to know how to handle flash UI but more important should be highly skilled with action script coding.
The developer will have to develop a facebook timeline embadable video player which play youtube video along with a mp4 stream. The 2 stearms should play in sync handling many different cases like video buffering, differnt YouTube video quality etc...
The project requires some research as well.
The developer should speak fluent english and will need to pass skype interview.