Here is the small sized YouTube version,
It's latest YouTube Lite app,specially designed for smartphones with low RAM.
Advantages:
1.it don't requires Google play services update to latest version
2.it is of just almost 2 MB
3.it takes no RAM
4.it is faster,lite and easy to share.
5.with swipe option to view trending videos.
Disadvantages:
1.you can't upload videos
2.you can't save offline videos.
Disadvantage of YouTube Full version:
As the new version us of 28MB and it consumes 65MB RAM of your android.it consumes more battery and also requires latest google play services version.
So,don't take risk to destroy your mobile.just download YouTube Lite app.