Parsec lets you invite your friends to play games with you online even if the game doesn't have online multiplayer. You can play together, watch them play, or take over the controller to show them how it's done.
You might get falcon kicked, but it won't be because of lag or frame drops. Play local multiplayer games online, watch your friends beat that final boss, or pass the controller with Parsec.
You can jump into any game and meet new people to play games with through Parsec. It's just like heading to your local arcade and finding someone to matchup against in Street Fighter.