There are some commands you can't repeat which are: sit, stay, down, off, quiet. Then you have the commands which you can repeat which are: come, heel, and bed. When the dog sits you immediately follow the sit command with stay. If the dog lays down instead of sits it's okay because that is just a lazy puppy sit.
In the video you'll see Duke trying to play with the leash. This is his first day of training so he is a work in progress. To teach the Drop/leave it command you first put your elbows to your rib cage so your arms are not being pulled out especially with a dog of this size. Look the dog straight in the eyes and say drop it. You may repeat this command in the beginning while they are leaning, but once they know it you do not repeat the command and then you may incorporate the No. Don't give up and don't let go. As soon as they release say leave it. If you don't say leave it after they drop it they will go after it again. If they grab it again say no drop it!