Hi,
This one was a little more challenging because the model isn’t round (+ that neck and face) … 
That’s horse anatomy for you !
Although ears and mane were quite easy to create the nose was the hardest part (to make it actually look like a horse’s one)
I didn’t use the same method as in the video to “flatten” my model (Time: 11:20-11:30).
I used the fact that the median point of a “horizontal” edge loop isn’t on the X=0 plane (or Y=0 plane depending on the mirror properties) so when scaling >1 the geometry becomes somewhat longer than wide just like I wanted it 
I’m happy with the final result 
Cheers !