Grip Claw not increasing duration of Infestation to 7 Turns

[InXSible 1]

Infestation is normally a 4-5 turn trapping move, but when equipping a grip claw, it should be increased to a fix 7 turns; at least in gen 5 and up. But as shown from this video, infestation only lasted 5 turns even with the grip claw equipped. 

 

http://www.youtube.com/watch?v=t9GRaDvW4FI

 

This was done in the latest episode with no mods attached.

Originally, This was found in the Redux Mod 18.6, using a gastrodon with infestation, so I wanted to see if it was the same case in a clean, unmodded game.