I can't look at the video posted.
However, you didn't really include enough information to provide specific help. Generic advice...Fermentations can stick due to:
1. Very high gravity beers
2. Old yeast
3. Not enough yeast
4. Rapid or repeated temperature drops greater than 1 degree C
High gravity beers are a completely different animal.
2-3 can be solved by using new large dry-yeast packets (similar to the SAFALE 11.5g packets), or by growing a starter or the appropriate size. Also, good oxygenation of the new wort makes a big difference.
4. Any number of different methods for controlling fermentation temp.
a. Ice bath to cool
b. Heating pad to warm
c. Place the fermentor in the most stable part of the house (noth/east bathroom bathtub...basement, etc).
d. Refridgerator with heating pad wrapped around fermentor
According to Chris White: Temperature drops faster than 1 degC per hour will cause some of the yeast to shutdown and begin preparing to hibernate. Then they floculate and drop to the bottom of the fermenter. Warming the fermenter back up and rousing the yeast can help. But, once they have floculated its hard to get them back into "permenent" suspension. Every cycle like this will drop more yeast out.
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If I just wanted to be sure it was going to work, and make decent beer...I'd buy brand new SAFALE US-05 packets.
1. I'd cool the wort to pitching temp (2-3 degrees below desired fermentation temp),
2. then I'd oxegenate it with a lot of shaking, splashing, or an oxygen stone.
3. Then sprinkle the a brand new SAFALE US-05 directly on the surface of the wort.
4. I'd leave the lid loose for 48-72 hours, then I'd cap the lid, and fill the airlock once it was at high-krausen.
5. I'd keep the temp as stable as I could (basement, or a NE bathtub with water in it).
6. Then I'd leave it alone for two full weeks...just looking for bubbles in the airlock.
7. After two weeks, take a gravity reading...wait two days and take another. If it drops, give it another week and try again.
8. Once stable FG, then you can start any clarifying steps you wish, and then bottle or keg.
NOTE: airlocks don't always bubble...or rather, buckets don't always seal well enough. So, you need to know if your airlock is going to bubble based on previous experience.
When you get this down, and it works every time...then you could start thinking about changing it up: using a different dry-yeast, using liquid yeast, making a starter, etc. I would progress in the order listed. Dry yeast is certainly easiest and most fool proof (assuming viable yeasts). Liquid yeast isn't much more difficult, but it can sometimes fool you direct from the vial. Making starters adds a little more complexity. It helps to have a foundation of experience to rely on, when adding a new layer to your bew process.
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Here is how I do it:
For general beers I make a 1L starter 48 hours before brewday on a stirplate. On brewday morning I decant the spent wort, and add fresh wort back to the yeast.
After brewing, I cool the wort to 3 degrees below desired fermentation temp. I aerate the wort with an aquarium pump for at least 30 minutes. Then I pitch the entire starter (wort and all) into the wort.
I continue to aerate the wort for another hour or so. It helps to stir the yeast around into the full beer and they get some "extra" O2 for that first hour. I will see visible signs (krausen, churning, etc) of active fermentation within an hour of removing the O2 stone.
I keep the fermenter in my wine closet with a temperature controller attached to a heating blanket. I let the beer ferment for 12 hours with the controller off. In this time, the wort will warm up 2-4 degrees. Then I turn on the controller and set the control point to the current fermentation temperature.
I leave the lid on, but keep it loose for the first 48-72 hours of fermentation. I take a couple samples for various readings during this time (to make sure that fermentation is proceeding as I expect). At the end of this time, I lock the lid down and fill the airlock. Then I take samples and measurements once/twice a week until fermentation subsides and FG stabilizes (2 weeks). Once the fermentation has subsides, I raise the temperature 4 degF for another week.
Then crash-it, and keg it.
The above schedule works. I've NEVER had a stuck fermentation. I can do it the same way every time without having to take too many measurments. It could be shortened, but I'm not in a rush...Going faster would require me to take more measurements to verify fermentation has completed before moving on.
Here is a very helpful vid. Hope it helps http://brewbeeranddrinkit.com/yeast-attenuation-and-beer-fermentation-problems/