There is over 800 million people on Instagram. I love the fact that Instagram came up with IGTV. It made them competitive with YouTube. So my question why use IGTV?
1. You can reach a new audience. You can expand your reach while repurposing your videos. You can can reach so many more people. Plus now it's show up in the newsfeed as preview. Great way to get more reach.
2. You can be more creative. Maybe use different backgrounds or maybe to create buzz around something you are launching. And remember these videos are vertical and have to be under 10 minutes.
The most important thing around is it's another way to reach your audience.