To split the screen into two even halves you can use a LinearLayout
as the container, set orientation to vertical, and set the 2 children to have layout_weight="1"
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<ScrollView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_weight="1">
<!-- YOUR SCROLLING CONTENT HERE -->
</ScrollView>
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_weight="1">
<!-- YOUR VIDEOVIEW HERE -->
</RelativeLayout>
</LinearLayout>