The whole pack attack vibe in the video is a bit creepy but I respect the way comics have a code about stealing. If you're caught ripping material, you're pegged for life as persona non grata. Almost like a mafia thing. Rogan talks more about it here.
(Side note on the video: Note the power of the microphone. As soon as someone hands Rogan his own mic, the entire tone changes. Volume is a hell of a weapon.)
Other comics known for ripping off material: Denis Leary stole Bill Hicks material (Rogan talks about this), Robin Williams stole everyone's material (and is supposedly now banned from a lot of NYC clubs). Dane Cook's been accused of stealing from Louis CK and Rogan too. This Radar article has more on joke stealing.
On the flip side, there's gotta be some wiggle room for two people coming up with a joke independently. A lot of creative minds think alike. The "Who's gonna build the wall to keep the Mexicans out?" bit isn't exactly the most original joke I've ever heard.
Also, there's an argument to be made for subconscious leakage here. I can totally see how someone who listens to comedy nonstop and is in the clubs all the time might pick up ideas for material without realizing it. But still, if it's a pattern of behavior, that ain't right.
I've already buried a couple jokes that I came up with on my own. The inconvenience store bit. And I recently had to toss this bit too:
I like when guys come up with these sex acts that humiliate women and then give them strange nicknames. I make up new ones. "That chick I was with last night...I gave her a Detroit Suitcase." That's when you're eating a girl out, you vomit on her, and then you throw her out the window. It's really fucking hot. Or there's the Velvet Porcupine. That's when you she's giving you head and you cover her with honey and then you release a swarm of bees in the room.
Another comic told me Patrice O'Neal does a big chunk on the same topic (I've never seen him). I guess I could go ahead and try it anyway since I did come up with it on my own, but it ain't worth it. As someone starting out, I really don't want to get tagged as a thief.
Besides, it's good inspiration to come up with material that's more personal and authentic to myself. The more you get to a specific, personal truth, the less likely it is that someone else will have covered the same ground.