Tam,
The twitchy retrieve just adds a bit more action to the fly that's all . Sometimes the fish like that , sometimes not.
The video link I watched is not the one described above by jimmymctavish.
I can see the point in this video if there is some instructional point being made in it but there is,nt.
It's just basically an ad for Lochter showing someone catching a trout to some background music.
I,m puzzled by the description.