There's a lot there to talk about at that link, much less refute in the limited space here. Nor do I have the wealth of arguments available at hand to extensively refute everything there. Volumes have been written arguing both points of view. However, this graphic says it all:
For Connally to be hit by the same bullet he would have been sitting much further to the left when he turned to look behind him.
I don't believe Oswald was the lone gunman. But I do think he was one of more than one gunmen. I also think he fired at least 2 (of a possible 4) shots at Kennedy, at least one of which hit Kennedy. Probably the one where he holds his throat. I think he probably missed JFK and hit Connally with a second shot. However, I think the headshot came from another gunman standing behind the grassy knoll.
He WAS sitting much further to the left you goob! You chose the graphic they posted on the web page as an example of how far the conspiracy theorists have to go to lie to attempt to disprove the single bullet fact. The ENTIRE rest of the web page goes on to prove Connally was sitting to the left, was sitting lower on a jump seat, was turned around (not facing forward like your graphic shows), and had wounds that lined up in a perfect line directly back through Kennedy's wounds and directly back even father to the vicinity of the 6th floor window of the TSBD.