I have done Skype messaging, but I have never, ever been asked to do a video chat, nor would I ever agree to it. I even find video chatting with friends and family immensely distracting with bobbing heads, sudden disappearances, and overloud, stilted. conversation.
Well this is just my two cents worth, but I would'nt even do the video chat with you.
Im sorry, but you kind of come off as being overly controlling and even a little creepy making such a request. And on top of that, I'll bet a lot folks are like me. I only video chat with someone I know and am comfortable with... not total strangers... potential client or not. I would actually consider a request like that invasive and yes, I would probably report you too.
My guess is that you inadvertly scared or creeped those freelancers out, weither you realized it or not.
As far as making a determination of a freelancer, well thats what portfolios, test results, and feedback are for. If all of those look good, then odds are the freelancer is fine. Yes, there are scammers around... there always are. However I have yet to see one of those profiles that actually has a number of positive feedback remarks on it. They usually dont have any. I have yet to see one that has a great rating. They usually dont have one at all. And has pointed out already, a simple phone conversation will usually tell you all you need to know.
Upwork isn't perfect by any means. But they are pretty at good weeding those guys out and do on a regular basis.
The best way to protect yourself is, not to pay a contractor unless they've completed the specifications for the milestones or entire job (however it's set up.) And to make sure all the financial transactions are done on site. Sure you might waste your find by finding a contractor who is taking way too long to complete a job, or who stops communicating and disappears, but at least you'll still have your funds.
re: "How to know fake freelancer?"
I'm still laughing about a profile I saw from somebody in another thread.
He claimed to be form "Newark, India" and claimed to have a Masters degree from "XYZ".
Things like that are pretty good signs you might be dealing with a fake freelancer.