You can log your browser's traffic to see the actual GET or POST requests. Use Fiddler or something like that. And then you'll be able to reuse them with http client.
is it possible, but I would say it is extremely difficult, each site will have a unique set of parameters you will need to manually fill, youtube I would guess is very complex
You need to add resource with type "LinesFromFile" which contains email:pass lines. Than use it in any action(Load, input text, etc) with Add resource button http://prnt.sc/cmhqqe
