examples/with-video-background/App.js

import { Video } from 'expo-av';
import React from 'react';
import { Animated, StyleSheet, Text, View } from 'react-native';

export default function App() {
  const opacity = React.useMemo(() => new Animated.Value(0), []);

  return (
    <View style={styles.container}>
      <View style={styles.background}>
        <Animated.View
          style={[
            styles.backgroundViewWrapper,
            { opacity: opacity }
          ]}
        >
          <Video
            isLooping
            isMuted
            positionMillis={500}
            onLoad={() => {
              // https://facebook.github.io/react-native/docs/animated#timing
              Animated.timing(opacity, {
                toValue: 1
              }).start();
            }}
            resizeMode="cover"
            shouldPlay
            source={{ uri: 'http://d23dyxeqlo5psv.cloudfront.net/big_buck_bunny.mp4' }}
            style={{ flex: 1 }}
          />
        </Animated.View>
      </View>
      <View style={styles.overlay}>
        <Text style={styles.title}>
          This is where you might put a button or some other text on top of
          the video
          </Text>
      </View>
    </View>
  );
}

const styles = StyleSheet.create({
  container: {
    alignItems: 'center',
    backgroundColor: 'transparent',
    flex: 1,
    justifyContent: 'center'
  },
  background: {
    ...StyleSheet.absoluteFillObject,
    backgroundColor: 'black'
  },
  backgroundViewWrapper: {
    ...StyleSheet.absoluteFillObject
  },
  overlay: {
    ...StyleSheet.absoluteFillObject,
    backgroundColor: 'rgba(0,0,0,0.4)'
  },
  title: {
    color: 'white',
    fontSize: 20,
    marginTop: 90,
    paddingHorizontal: 20,
    textAlign: 'center'
  }
});