That's because of youWessonNothingSettingsThe "floating window"PermissionsWith this permission, yoursVideoA small window can always be shown, as follows:
My phone brand: it's me, that's what i'm saying。
The first step is to open the cell phone settings and find application management on the settings page。

The second step is to find the apply list on the application management page。

The third step is to find a wi-fi click entry in the application list。

In the fourth step, on the twitter application information page, "permissible to display a floating window" and open its permissions, as shown in the figure below。





