Inviseble hack?

I was playing in junk vleaand this guy was killing everyone but nowone could see him.So we say : *facking invisible hacker leave!*
Then he say: * I hack so what it's in the game...*
then he leaves.
And comes back again
And still nowone see him but i can here him walk xD and shoot and see bullets.....Is this *Invisble Hack* Is there a hack like this?
I saw it in a video on youtube too:

[YOUTUBE]<object width="445" height="364"><param name="movie" value="http://www.youtube.com/v/Y4fEOo5I7wM&hl=nl&fs=1&color1=0x5d1719&color2=0xcd 311b&border=1"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/Y4fEOo5I7wM&hl=nl&fs=1&color1=0x5d1719&color2=0xcd 311b&border=1" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="445" height="364"></embed></object>[/YOUTUBE]

[YOUTUBE]<object width="445" height="364"><param name="movie" value="http://www.youtube.com/v/JaPqGdrDgPo&hl=nl&fs=1&color1=0x5d1719&color2=0xcd 311b&border=1"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/JaPqGdrDgPo&hl=nl&fs=1&color1=0x5d1719&color2=0xcd 311b&border=1" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="445" height="364"></embed></object>[/YOUTUBE]

And the best one:


[YOUTUBE]<object width="445" height="364"><param name="movie" value="http://www.youtube.com/v/wNRIsyABVEQ&hl=nl&fs=1&color1=0x5d1719&color2=0xcd 311b&border=1"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/wNRIsyABVEQ&hl=nl&fs=1&color1=0x5d1719&color2=0xcd 311b&border=1" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="445" height="364"></embed></object>[/YOUTUBE]