This type of behaviour does not only happen on Ryanair remember?
We have but one side of the story too. I will hold off until I get both sides, they could have both been as bad as each other, but we don't know do we?
I wonder was he quiet for the rest of the journey? The other passenger did not like his body odour, so maybe she said something to him that riled him too.
The fact that he was not kicked off gives me a signal that both sides were at fault perhaps. No one else on the plane apart from the man behind did or said anything, but filming it was no problem at all for others.