Not sure what peoples definition of cuckolding is. The dictionary definition is a married man who's wife has sex with another male. Nothing to do with humiliation, watching or joining in. 

Any guy whose wife fucks someone else either with or without his knowledge is a cuckold.

Ive attended a few gang bangs as a fluffer and cleaner upper and they have all been well attended. In one case more turned up than expected and the lady struggled to satisfy all of them. lucky her. LOL