His "simple dirty tricks" to run a successful RP session are:
0. Have a goal for the session (this is more of a general bit of advice he gives)
1. Introduce a backstory NPC (AKA a new NPC related to a PC's backstory)
2. Introduce a third party (to complicate the RP with a new agenda)
3. Set the PCs up for a fall (a bait and switch/manipulate their emotions gambit)
4. Create a moral dilemma for the PCs (orc babies, anyone?)
5. Introduce a new ally or enemy (how this is different from #1 is...the new NPC is not related to a PC's backstory, how it's different from #2 is...I'm not exactly sure, unless the "third party" in #2 is completely neutral in whatever conflicts are going on)
My first impression is that aside from one of the "dirty tricks" (#3), I wouldn't consider any of these to be dirty tricks. But with the nature of click-bait titles, I'll let that slide. He needed to jazz up the title to get people interested. And in my case, it did work.
So, first of all, his idea to "have a goal for the session" seems to imply that the DM knows and is planning for an RP session. My philosophy of GMing any more is to never have a goal for the session as GM. It's the players' responsibility to come up with goals for the session. If they decide to just hang out in town chatting up NPCs, THAT is apparently the goal they have come up with for the session.
That said, if the players do opt to RP the entire session instead of exploring or hacking & slashing, his five bits of advice of things to throw into the session to liven things up aren't all bad.
#1 seems to imply coming up with a "backstory NPC" off the cuff. While that's certainly possible, I've found through the years that throwing in an already established NPC works better. We've already got an idea of the NPC's character, and the players may familiar with the NPC's attitudes, goals, etc.
I did this intuitively as a kid. My best friend's main Fighter had a 3 Charisma, and tended to piss off otherwise friendly and helpful NPCs. If we were in a long RP session, I could usually find a way to work in one of the "Caric's Enemies Club" to the game and have some fun interactions with an established NPC.
#2 seems to again be premised on the idea that the DM is running the players through some sort of predetermined story. Having multiple factions that the players are free to oppose or try to ally with is great. And if there's a lull in the dungeon delving, it is in fact a good time to introduce new factions to the players. If you're trying to run the players through some kind of specific plot (whether it's predetermined or just heavily guided to try and steer things a certain way), this is actually a good way to derail that story! The players may find the new faction more engaging than the current allies/enemies, and want to totally switch gears. I'm actually all for that. But I don't think that's what the guy in the video intended.
#3 can be a real dick move, if not done right. And the guy making the video does warn you not to overuse this idea. The problem I see with it it, if you don't plan this ahead of time, it won't have the emotional payoff you're hoping for. And if you do plan it ahead of time, and are just waiting around for the players to disengage from the exploration and talk to the NPCs for a session, it will feel contrived when you trot it out. Now, if you're running them through some sort of story, and you know you'll have a break in the narrative, yeah, this would be a good time to use something like this. But if you are just providing a game world for the players to explore, this sort of thing should come up naturally as part of the in-game cause/effect of player actions/reactions. It's not the sort of thing that should be planned and "sprung" on the players just to try to manipulate them emotionally.
#4 shouldn't be something the DM forces on the players. The DM should always be giving them situations where they have choices to make of a moral or ethical nature. But I can't, as DM, force the players to engage in the choice as a dilemma. That depends on the player's mentality and how they envision their character.
In my experience, since RPGs are NOT the real world and the consequences aren't real to the players, they will happily take a situation that might actually be a dilemma in real life and easily choose to do one thing or the other. A writer can decide that Hamlet can't decide whether avenging his father or not betraying his king is the morally correct action. As a DM, all I can do is dangle the situation in front of the players. Whether they decide to ignore their father's ghost, run straight to the throne room and draw steel, or spend days moping around fretting about the decision is out of my hands. It's my job to take their decision and roll with it, and play it out.
And if there is a dilemma, it's usually not every character fretting over the possible courses of action. It's a debate between PCs that have made opposite decisions. And they will happily debate it out in character (and sometimes out of character too) while I just sit there and listen.
#5, as I noted above, isn't really any different than #1 or #2. They're all basically trying to spice up an RP session by throwing in more NPCs to interact with. And that's fine. If the players have decided to hang out in town and do research, pursue personal goals, or just have a laugh, the more and more varied types of NPCs they have to interact with, the better. This point just suggests a different type of NPC to throw at the players compared to the first two "dirty tricks."
So looking at the specific points offered, yes, these are usually good ways to spice up role play encounters. In fact, they would mostly work even if it's just an encounter, not an entire session. The problem I have with the video's premise is that it expects the DM to be providing some sort of coherent narrative for the players to move through. That's not the DM's job. The DM should set the stage. The DM should be reactive to the actions of the PCs more often than they should be actively trying to "move the plot" of the game.
If the DM plans for an RP session, and prepares one of these "dirty tricks" to use, but the players aren't in the mood for an RP session and would rather get on with the adventure, then it's going to be a dull or frustrating session for everyone.
So budding DMs, don't force it. If you find your players in the mood for some heavy RP instead of exploration/combat, remember these "tricks" as things you can do when things seem to slow down and you need to add a bit of spice. Just don't force them upon your players.
Inexperienced players, force it! If you're in the mood for role play, role play away! If you want to explore or get in a fight or whatever, let the DM know that's what you want to do.
The best RP sessions aren't pre-planned or forced. They just happen spontaneously.