I think Witchy and others here are better to give advice than me, and I can't say anything in response to Savannah cats in particular, but with animals in general I have found the foundation of building a trusting relationship is them learning we can usually be trusted to listen to them and respect their boundaries. That when they say no with their posture or a subtle movement away, we will listen and respect them. And with animals it is usually a lot more about body language. By the time they start vocalizing they generally feel we did not get the message the first time.
If it was me, I would spend time laying a foot of two away, but beside Alpha, and depending on whether he relaxes with that, maybe reaching out a finger and just laying it on a paw. If he flinches away I would remove it and just go back to laying there. If stays relaxed and e accepts, or even relaxes more enjoying touch as reassuring, I would just let it sit there. Nothing else. A light touch of respectful friendship. After a few times of hanging out like that I would try some very limited subtle gentle stroking a 2 inch area with that 1 finger. Again if he flinches away I would stop. If he accepts that and becomes more relaxed in response, I would very gradually progress to more, but listening for any signals you are patting him without it being enjoyed by him, and as soon as you get that signal stopping and even backing off a bit.
Except in this situation as Witchy noticed, the cone may make contact with a part of his body he can't see scary for him.
But I am thinking in this video probably you were just wanting to provoke a strong reaction so you were pushing him, and this is not showing a typical exchange between the 2 of you...