Can migrate O365 Video to Stream at one to go and same time?

Blue-01 Hi, yes you can do this Microsoft are providing a migration wizard, if you haven’t already, check the roadmap for specifics: 

https://docs.microsoft.com/en-us/stream/migrate-from-office-365

Basically, there should already be an option to migrate all content to Stream or there will be soon, this takes you through the whole process and the required preparation: 

https://docs.microsoft.com/en-us/stream/migration-experience

Check the ‘What gets migrated over from Office 365 Video to Stream?’ for full details on what will be migrated and the limitations.

Or you can wait and automatic migration will start from next month, per the first link, review the Message Center for the latest information (in the admin portal), which will have guidance and availability for these migration options specific to you tenant.