Not sure how this would work in the UK but if this isn't old someone with a reddit account tell him to continue asserting his innocence, put that video online, on other drives, in the hands of as many people as possible. If he can prove she cheated on him and that he never laid hands on her he should get his house back... eventually. Sadly he is going to have to pay for this mistake by taking a vacation from the house.

Find a friend or family member to crash with because this might be a long time, and pray she doesn't destroy too many of your possessions in the intermedium. Do NOT go to the house, do NOT confront her, do NOT seek petty or terrible vengeance. Yet.

The video should not be made public unless UK law would actually side with the wife, then it could be used to draw public attention to what happened to him.

@Humpleupagus not sure how familiar you are with UK law but tagging you if you have anything to add.