Instagram's Hyperlapse uses the sensors in your iPhone to stabilize video on-the-fly. That way you get silky-smooth time-lapse video, at up to 6x, of stages being built, forests being run-through, highways being race by, and anything else you can imagine. What you can also do, however, is choose to save the video at 1x. And what that does is create silky-smooth regular video. So smooth, in fact, it looks almost like it was shot for a steadycam. That's not only great for tech writers trying to cover new products solo at an event, but for everything from shooting a birthday cake in motion to an impromptu ukulele jam. You'll need to pay close attention to how to save the file, but otherwise using Hyperlapse for rock-solid video is easy to do!
You can always record your video using the built-in Camera app, of course, and then load it into iMovie, Final Cut Pro, or another editor and apply stabilization as part of post-processing. Hyperlapse, however, lets you stabilize as you capture, so if you want to upload to YouTube or Instagram or otherwise use the video immediately, right from your iPhone, it's already good to go.
Note: Hyperlapse doesn't keep the original video, so once you save it out, you're done. That means you absolutely, positively have to choose 1x before you save or your steadycam video will irrevocably be rendered as a Hyperlapse with no going back.