Hello,
Yes, you can build your own VideoCall server using WebRTC, there are some demos which show this: WebRTC and AppRTC demos.
Trial version doesn't include sources, but includes compiled files, those are located inside libD10_2 folder. If you open sgcWebSockets package and try to modify some properties of it, Delphi delete some compiler defines, so better download again the trial and follow these instructions:
https://www.esegece.com/help/sgcWebSockets/#t=Install%2FInstall_Package.htm
Kind regards,
Sergio