Showing ID would work, but a video call? I've worked remotely for years - why would half the people in IT know my face from some other dude?
- compare the person with an ID on file
- invite the manager or a colleague of the person into the call to confirm
- ask for PII (birthdays, address) that are on file
I assume someone assuming the identity is more reluctant to show themselves on video. Furthermore being asked PII they are likely not as prepared.