IGTV wasn't as easy as it seemed. I realised that the best option on IGTV is to shoot vertically on your phone and upload it straight from he camera. Because uploading your high end videos and content is harder than you think especially if you are a "normal" person (who is non viral and have a few subscribers).
I too watched marquesbrownlee and head to IGTV to make my Channel. And then when the Moment guys spoke about it I was completely convinced this was the next best thing.
Thanks to my Dad I had a vertically shot film on Bhutan which was ready to edit and upload. Which I did. However uploading to IGTV wasn't as easy to upload
My Problems were
1. Crop the edit from landscape to portrait which was promptly solved by Latesha James (see her youtube channel she’s amazing)
2. The fact that the video needed to be UNDER 10 minutes max my 11 minute video was not excepted. So after much trial I eventually uploaded a 9:55 minute video and it FINALLY got accepted.
3. My file needed to be under 650MB in size which is hard so I had to downgrade my 4K and export it in 720p mode which wasn't fun.
This was my experience which made me appreciate YouTubes inclusive file size, length size and horizontal mode. But IGTV pushes you to really shoot and edit from and on your phone. So that would be more fun to see in time.
Till then check out the other video on IGTV on YouTube and let me know what challenges and solutions you found on IGTV.