It’s important to note that stitching to a video with one of your own and dueting one are both different features. When you stitch, you take a small portion of someone’s video and make a continuation of sorts with your contribution to the video. When you duet, you use another user’s video to allow it to play as yours plays alongside it.
You might be thinking by now that TikTok is a young man’s game, but rest assured, everyone is usually at least a little bit confused when they try to figure out a new feature. Luckily, TikTok makes it pretty easy to understand how to use these little features and, if you stay up to date, it will become like second nature for you to get the hang of them too.