Your opening gambit must always be: everyone online is a liar. How can you possibly know who's who? Anyone can pretend to be anyone. Anyone can use anyone else's photo. He'll be found out eventually but in the meantime you must be 'social network smart'
If a GB member was online, he would not include GB in his username , for the phrase does not belong to him alone. He would also not do it without printed or web material stating beforehand he was using a new channel of communication. He would not change his username like a snake - probably to keep one step ahead of whoever. A cover frame on a video is no guarantee as to what's inside. They do indeed have to fend off many accusations. 'Fake News' is a huge topic in the news today and it is seemingly everywhere. One would think deliberately impersonating and defaming another would be punishable by law.
The Internet is not the congregation. You can't have your own personal congregation there. Where is the channel for spiritual food? Where are the elders? Where are the trusted people you know? So anyone you do not know personally you must assume are liars. To be safest, you friend only those you know. For better or for worse, I will friend brothers I don't know. As long as they behave, they remain friends, for an internet friend and a real friend is not the same. But I don't quickly trust them and what trust I do extend can be withdrawn in a second, for I can't possibly know them as I would somebody in my congregation.
What do the verses say?
'We ask you not to be quickly shaken from your reason nor to be alarmed either...by a letter appearing to be from us' 2 Thes 2:2. Somewhere there is an article about not jumping to conclusions regarding ones who have earned trust. Somebody find it.
'The thief does not come unless it is to steal or to slay or to destroy' John 10:10
This is a fine (at present and so far as I know - to the extent it is correct, it may have been updated) online resource
It's probably well not to speak with a liar. Do not think others have not done so. With someone not a liar you can discuss and persuade, but not with a liar. Witness discussions online about anything - politics, for example. People do not patiently hear the other side out and weigh the issues. No. They are like football fans. They cheer when the home team scores a point. They wince when it incurs a penalty or suffers injury. But at no point do they suppose the other side is anything more than evil incarnate.
Tom Irregardless and Me. 30% free download.