Improvisational videos 1,000%. Scripted/cut videos aren't natural, and the improved "quality" isn't worth it to me. It makes watching it choppy and annoying on my eyes. I also prefer when someone can make direct eye contact with the camera, so it feels more genuine. When people are reading lines, their eyes are always moving left to right, and their delivery is mechanical. Videos that flow and are imperfect (showing the person's natural personality) are the way to go in terms of my vote.

Furthermore, your skills will sharpen as you make more videos.

When in doubt, do what's more fun for you. You'll obviously have a few planned main points to make, but it's nicer to watch you get to them on your own, instead of feeling like it's so formal/trying to be perfect.

The only caveat is that dtube's videos aren't hosted for super long if you don't meet certain conditions. If you want to keep your video content alive longer, save the files or back them up on YouTube (cough).