It's the test footage for the film and they used cgi because of budget issues. It wasn't approved by Fox (not PG-13?) and the voice is suppose to be Ryan Reynolds in it, it did sounds like him too.
...back in 2012, the Merc with a Mouth's creator, Rob Liefeld, revealed that Miller, who signed on to helm the solo adaptation back in 2011, had developed test footage with his visual effects company Blur Studio. This footage was also seen by the film's screenwriters Rhett Reese and Paul Wernick who both confirmed Ryan Reynolds had performed the motion-capture and provided Deadpool's voice.