I, like Ironman, am going to break this down by submission.
Step over leg lock:
Like Ironman said, this requires little to no resistance on your opponent's part. There's no force/counter-force to this and it's really all muscle and quickness. The other thing this relies on is your opponent constantly keeping his guard closed, as opposed to opening it as soon as you being to rotate. Ironically enough, this move also sets you up for leg locks...
Knee bar from half guard down (hands free kneebar, as Ironman put it):
This is really a sort of flimsy submission. All your opponent needs to do it break free of your feet or put his knee to the floor. The opponent can easily rotate his hips and pass to quarter guard or go knee on belly WHILE IN THE SUBMISSION. That's not good. Very easy to escape.
Also, what you should do here is called an "Electric Chair" which is both a sweep and a submission and will be far more reliable than this.
Hip Flexor from Scarf hold:
This one is actually viable, but it also takes away part of your control from his head and arm, making it easier for him to escape. Also, as Ironman said, this is not common practice to attempt to escape scarf like that.
It's a basic kneebar... don't know what else you want on that. Also, when you do it, sit up closer to his head, it causes far more pressure and extension on his leg.
This I actually like quite a lot, but there are a few mistakes with it. I LOVE calf crushers (they're extremely painful) but I generally do them from half or side, cool to see one from guard. The part you need to remember here is that the pressure is on the knee and the back of the calf. Instead of putting your foot under him like you do, wrap it over his hips. This will do two things, stop him from rolling and cause far more pressure on that leg. You can also use that extra leg and put a sort of body triangle on, adding even MORE pressure. Extremely painfaul and effective, if you're quick enough to land it.
(after typing that I realize that IronMan just said the same damn thing -.-)
The only problem I have with this is that the instructor DOES NOT BOX HIS HIPS in any way. That's extremely annoying to see. You HAVE to control his hips to make sure he can't just roll out of it. As it stands, the victim could easily do that. Had he put his foot across the belly (like he does in the classic kneebar) it would be much more effective.