OpenTube - Open Video Player

OpenTube makes multitasking with YouTube easy. Watch videos in Picture-in-Picture, keep audio playing while your phone is locked, or even run two videos at the same time, one full screen and one floating. You can open up to three separate YouTube sessions and browse each one independently. 

Watch YouTube in Picture-in-Picture mode
Keep audio playing in the background with the screen locked
Advanced OpenTube controls for better multitasking
[Pro] Built-in YouTube ad blocking

Choose a perpetual, monthly, or yearly auto-renewable subscription 

This is a recurring transaction that will be charged to your iTunes account upon confirmation of purchase and will automatically renew. You can cancel your subscription at least 24 hours before the end of the current period. Renewal fees will be charged within 24 hours before the end of the current payment period. You can manage your subscriptions, and auto-renewal can be turned off in your iTunes account settings after purchase.

Terms of Use: https://www.apple.com/legal/internet-services/itunes/dev/stdeula/