tela_inicial.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"

    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".Aplicativo.TelaInicial">


    <include layout="@layout/videobackground"/>

    <TextView
        android:id="@+id/txtBV"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentStart="true"
        android:layout_alignParentTop="true"
        android:layout_marginTop="10dp"
        android:gravity="center"
        android:text="Bem Vindo"
        android:textAlignment="gravity"
        android:textSize="30sp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.0"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.013" />

    <Button
        android:id="@+id/btnCadastrar"
        android:layout_width="120dp"
        android:layout_height="50dp"
        android:layout_marginLeft="50dp"
        android:layout_marginTop="200dp"
        android:text="CADASTRAR"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.603"
        app:layout_constraintStart_toStartOf="@id/btnLogin"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.172"
        tools:textAllCaps="false" />

    <Button
        android:id="@+id/btnLogin"
        android:layout_width="120dp"
        android:layout_height="50dp"
        android:layout_alignParentRight="true"
        android:layout_marginTop="200dp"
        android:layout_marginRight="50dp"
        android:text="LOGIN"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.284"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.172"
        tools:textAllCaps="false" />

</android.support.constraint.ConstraintLayout>