Use SuziLoader
This loader will load the thumbnails for the videos which is locally stored on your filesystem.

String path = Environment.getExternalStorageDirectory().getAbsolutePath() + "/video.mp4";
ImageView mThumbnail = (ImageView) findViewById(R.id.thumbnail);

SuziLoader loader = new SuziLoader(); //Create it for once
loader.with(MainActivity.this) //Context
	.load(path) //Video path
	.into(mThumbnail) // imageview to load the thumbnail
	.type("mini") // mini or micro
	.show(); // to show the thumbnail

To get this dependency use the following steps

Step 1. Add the JitPack repository to your build file
Add it in your root build.gradle at the end of repositories:

allprojects {
	repositories {
		...
		maven { url 'https://jitpack.io' }
	}
}

Step 2. Add the dependency

dependencies {
	compile 'com.github.sushinpv:SuziVideoThumbnailLoader:0.1.0'
}

ADD READ EXTERNAL STORAGE Permission in manifest

<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>