A bloke who was the best man at his friend’s wedding has been hailed as a hero online after he managed to film the moment he walked in on the bride getting up to no good with a bartender.

In a clip shared on Reddit, the woman – named as Nina – could be seen climbing off the mystery man’s lap, while the man behind the camera asked her what she was doing.

He said: “What are you guys doing? Nina, what’s going on here? Tell me what’s going on.”

And the woman replied: “You know exactly what’s going on here.”

A woman with a pixelated face who is wearing a white t-shirt. There is a man behind her wearing a white shirt.

The man filming the encounter then stated that the other man is not Nina’s husband, before telling the mystery man who he was.

He explained: “I’m James, I was the best man. This is Nina, this is my best friend’s wife.”

James then asked the other man if he was the bartender, to which he replied: “Not only, but yes.”

He then told the pair to “have a good night” before the 40-second video ended – and people in the comments couldn’t believe the woman’s scandalous behaviour.

One person wrote: “Hope her husband doesn’t give her another chance. She will do it again and he will never trust her. Dump her.”

While another said: “Good for the groom’s best man finding out. Hopefully, the dude leaves her with nothing but her regrets.”

And a third posted: “This makes me so sick to my stomach. So sad, hope the groom has healed and found someone truly loyal if that even exists in this world now.”

Other commenters heaped praise on the best man for living up to his name.

Someone said: “We all need a best man like him.”

And someone else wrote: “Best man truly being a best man and looking out for his friend.”

The video has gone viral after it resurfaced recently, several years after it was originally posted in 2014.

When the clip was first posted online, it was explained Nina had been married to her husband for just 18 months when the incident occurred – and he has since dumped her.

Text explaining the video at the time read: “After finding out, the husband went home, took the car, took her ring, and told her she had until the end of the day to move out.”