The best downloader app is here, and it's called Downloader Master - Player. What it does is help you download videos in HD from various websites, such as Facebook, Instagram, Twitter, Vimeo, YouTube, Dailymotion, and many others. In a single place, you can download all of your favorite videos and enjoy them in your preferred quality - you can opt for the 144P if you want to save some storage space, or go for the 1080 HD option if you just have to enjoy the visuals to the fullest. 

You can also choose neither of these, and download only the audio - the video is instantly converted to mp3 format.