@Florian Hein - Correct if an O365 Video link or embed code is still be used in March 1, 2022 then it will need to be manually changed over to it's Stream link equivalent.
We don't have hard plans on this yet, but we are considering if we need to build some sort of report or tool to tell customers where they have old active O365 Video links being used so a report could be run before March 1, 2022. We have lots of time between now and then to figure out if we need this or not.
Best Response confirmed by
Florian Hein (Regular Contributor)