This video shows 2 different ways to fix the "Movie recording has been stopped automatically" on Canon 600D. This is one of the World's shortest video in fixing this issue... 
 
Cause: 
A slow (wrong class or incompatible) sdcard might make the system not keep up, and abort a movie recording. 
 
Fix: 
1. Purchase an Extreme SD card 
2. Lower down recoding size.