NewPipe

Lightweight YouTube frontend that's supposed to be used without the proprietary YouTube-API or any of Google's (proprietary) play-services. NewPipe only parses the YouTube website in order to gain the information it needs. NewPipe has been created with the purpose of getting the original YouTube experience on your smartphone without annoying ads and questionable permissions.

• Newpipe.schabi.org
• F-droid.org-Newpipe

VLC for Android

VLC media player is a free and open source cross-platform multimedia player that plays most multimedia files as well as discs, devices, and network streaming protocols.

This is a BETA version of the port of VLC media player to the Android™ platform. It plays both audio and video.

MX Player

MX Video Player is one of the better media player apps out there. The app can access all video file formats and includes a lot of options that you can use to change the viewing environment of your videos

Viral Lite (Youtube Player)

Viral Lite is an innovative Youtube Player with many features
+Popup background play not allow from Terms service of Youtube
+Add or remove videos with Playlist system on your device