Might want to be extremely cautious
Not a good idea to be involved with people you don't know very well and fully trust. Never is it a good idea to become involved in any scene without talking directly to all involved or being present when his sub is explicitly agreeing to exactly what is to be done and even then take no part what-so-ever unless you know them very well.
If you aren't careful it could be the hardest lesson you will ever learn, always be suspicious of anyone who lets you be a part of any restraint scenes without knowing you very well, as it is likely they will teach you a lesson in making sure you took every precaution necessary to ensure you did have consent and that it was desired, blackmail is not fun and can turn your life into a living hell
I wouldn't even watch, unless I was close friends with all participants