What the Ryan did in that video was suggest that there was an Aspect in the game that wasn't written down but was obviously there based on what was being roleplayed. Wil and the others at the table agreed, and so Ryan compelled the aspect at the same time that he brought it up.
See Creating and Discovering New Aspects In Play
If you’re not looking for a free invocation, and you just think it’d make sense if there were a particular situation aspect in play, you don’t need to roll the dice or anything to make new aspects—just suggest them, and if the group thinks they’re interesting, write them down.
Here is another example that I just made up:
"The cavern entrance is quite small and has the aspect 'Covered with Slime'", says the GM. Tormund decides that he wants to make his barbarian's life more complicated and asks, "Could we make another aspect 'Tight Corridor'? I'd like to compel myself for a Fate point to get stuck."
Suggesting an Aspect is valid from GMs and players, however suggesting one just to compel it is tricky for the GM. Be mindful of your group dynamic. Perhaps your players won't appreciate these "surprise compels", or maybe they welcome you making their lives more complicated.