You guys are having fun together! It looks like you have a good relationship
I would recommend being much more animated in training. Make each reward a little event and keep him spun up and having fun. I tend to think of it like a play session, energy wise, with some OB training mixed in. When you mark a behavior, think BANG in your head and explode with some energy, always after the mark though. You can use the food like a toy by making it move and it will make the reward value greater.
When luring the AF, I would give the verbal separately from the lure. If you do the two at the same time it will take him much longer to fade the lure. Say AF, wait a half second, then lure. This also gives you a window to let him respond without the lure. As long as the lure comes within a second of the command, he will pair them.
If he knows DOWN, and you are trying to add AF, just say AF before DOWN through lots of reps and then remove the DOWN. He will learn that AF precedes DOWN and will begin to respond to the Dutch command before the english.
Good tip from Boomer about not dropping food. It takes the steam out of the training session while the dog hunts around for it.
Here's a great video from Baillif showing a short OB session.
Obedience with food game