Teams issue - "video sharing is disabled by the administrator" - when external users join first

halbpI wasn't able to get the exact same results as you (we have a meeting policy in place for our students to prevent them starting meetings so that only staff can start a meeting) but the result was the same.  Even after enabling "IP Video" in the meeting policy that was applied to students it was only when enabling "Let anonymous people start a meeting" were students able to use their webcams.

This doesn't make any sense as students are a member of our organisation and as such sign into Teams with their organisation account so I cannot see how enabling "Let anonymous people start a meeting" allows students who are not anonymous users to suddenly use their webcams.