I have the yongnuo 622's and the IR beam works well for night time shots, but it doesn't work with AI servo... which is a shame... because that would be nice to have it.
You're speaking of IR triggered off camera flash, or on camera flash? How would flash work with AI servo anyway? I tried a Yongnuo 560 and sent it back. I admit I don't know much about them, but I know I need E-TTL...
the 622's are transceivers that trigger off camera flash, but used alone, they will emit the red lines which aid in auto focus in darkness. using that alone would not blind the players and would help to lock in on your subject.... but it doesn't work in ai servo mode.