I think regardless of what we can see or not, BB is clearly indicating that something did happen of a physical/sexual nature. They would have other footage, but being 'family friendly' they wont show it... so they used what they could.
Also, Lawson's and Cat's reactions whilst the footage was shown, confirmed unequivocally to me that they felt embarrassed by being caught out. Lawson's pathetic diary room catharsis was all about him... how he was perceived... how this was going to impact on him. The token acknowledgement of his ex/girlfriend and her family was also about him, to make him seem redeemable to them/us with this and the tears.
He's playing the victim now, poor Lawson, letting down his deceased mother. I hope the public don't fall for it and save his sorry arse from eviction. His own confessions seems to add weight to the rumours that he is a serial cheater, and his contriteness, tears and damage control behaviour, seem like a ritual his ex/girlfriend has possibly seen before.
I've never liked the dude. Could never warm to him and I loathe magic, so it's no loss for me if he is evicted and has to face up to, take responsibility for and wear the consequences of his actions once he's out.
The only other HM evicted that I would see on par, is the weedy, seedy, beady-eyed aggressive, closet misogynist/abuser, self-entitled, control freak, SAM! He's loathsome.