In Stream Classic, the “group” tab shows you videos sorted into their corresponding Microsoft Teams team/channel. The videos you see here will often be meeting recordings and/or videos where a team has been added as an additional owner. The group tab will not be available in Stream on SharePoint, but your videos will still be associated with the team/channel they were associated with in Stream Classic, and you can group your videos into folders and libraries. If you want to display the videos associated with a specific team/channel with Stream on SharePoint, you have a few options. You can read more here