Knowing the width of the rail tracks in Chris's video is 4ft 8.5in, the animal photographed by him is clearly in excess of 4ft and as such is certainly not a domestic cat.
Look at the clip at the very start and at about 17 / 18 seconds and compare it to the width of the rail , it's a lot bigger than a housecat
 
	 
  
 
		
 
 
		 
		 
 
		 
 
		 
 
		
 
 
		
 
 
		 
 
		 
	