Cutscenes are one of those narrative tricks that a story-heavy GM like me enjoys.
The WEG version of Star Wars pushed them in published adventures, and they tend to pop up in media-emulating games in particular. So how do they work, beyond going “meanwhile”?
Keep it short.
Actually, keep anything non-interactive short.
(One option for a really big meanwhile sequence would be to make it interactive - hand out temporary PCs. Not all players like this, though - they’re here to play their characters, not a parallel team or a previous group of victims or the assassins out to hunt down the regular PCs. Sound them out in advance about the idea.)
Consider how much mystery and how much spoiler you and your players want. Err on the side of caution.
Too much can really affect future events, unavoidably, even for players highly adept at separating IC and OOC knowledge. As for mystery, I can manage the occasional clever plot twist, but I’m often bad at showing my hand too early. I’ve never managed a “no... I am your father” moment. (And consider how the prequels totally change the effect of that moment on fresh audiences.)
Consider genre as well.
In a pulp adventure game, revealing that the villains are laying a trap should encourage the players to send the heroes straight into it. In a horror game, the reaction would be rather different. A horror game might stick with the PCs’ point-of-view almost entirely... perhaps with the occasional cutscene of the PCs being watched by something out in the dark... A mystery game should probably not reveal things ahead of time - it turns a whodunit into a howtoproveit, and only Columbo really makes that work.
The PCs are on the run from an alien invasion. Their own little spaceship just jumped into lightspeed and escaped:
And on the bridge of the Tyranny command carrier, the fleet admiral rises from the command chair and turns to one of the bridge officers. “Find that ship!” he snarls, pointing at the viewscreen. “And remember, this time, I want them alive!”
This establishes that (a) they haven’t gotten away clean, which they should be able to figure out, (b) the fleet admiral has a bit of a temper but not a Darth Vader level of choking his minions, and (c) they’re wanted alive, which is apparently unusual.
The officer asking “You’re sure the homing beacon is secure aboard their ship?” would be painfully tempting to metagame, although it would make a great end-of-session cliffhanger with players willing to play along.