I've watched the footage a few times now. For starters, Irvin is clearly drunk but aside from that, I'd say the video shows him flirting with her and rather obviously at that.
As for her, I see several signs of her attempting to shut him down. She steps back and away from him more than once (0:15 and 0:39 marks). She doesn't appear to reciprocate in any way when he reaches for her arms at the 1:18 mark before taking yet another step away from him. The most telling signs occur at 1:23 and again at 1:28 where she seems to wave her hands across each other in a "no" gesture while he's falling over himself laughing. He also clearly steps towards her again at the 1:33 mark before they shake hands and wind the conversation down.
My guess, based on the video footage, is that Irvin was the aggressor here and she denied him. No idea what was said obviously but her demeanor was both professional and courteous in what was certainly an uncomfortable situation. Having said that, I would not have expected Marriot to pursue charges based on how the two left it but I guess they might have no choice.
As for Irvin's lawsuit, that one is easy. His pride and ego were hurt by some woman denying his advances, further exacerbated by the Marriot pursuing action, and he felt he had no choice but to counter with some absurd amount in an attempt to steamroll (which is pretty silly when you remember it's a corporate conglomerate in The Marriot).
Judgement for the woman in this case.