MinTube
Minimized/Floating Youtube
Download
Get It Here.
Or open bit.ly/mintube
in your mobile.
Source
There are two versions of the app : v0.90 and v0.91.
The only difference between v0.90 and v0.91 is that v0.90 shows icon on hiding and v0.91 shows a resized player on hiding the whole video player. All the other functionalities are same.
The above download link was for v0.90.
You can get v0.91 of the app here.