Use ZIndex as shown below. Doesn't have to be 5 or 10, just know that the higher the number, the higher it is to the top (from the viewing perspective of the user). The more complex the layout, the more handy this becomes.

<toolkit:Popup xmlns="http://schemas.microsoft.com/dotnet/2021/maui" ... ZIndex="5"> <Label Text="{Binding VideoUrl}" ... /> <toolkit:MediaElement x:Name="mediaElement" ... ZIndex="10"/> </toolkit:Popup>