Transitions

Where two clips meet there is a small chip on the boundary. Click it and you get a menu.

The three

Defocus blurs the outgoing shot as it goes and the incoming shot as it arrives. It is the one that reads as expensive, and it is the right default for a cut between two parts of a demonstration.

Cross dissolve shows both shots over each other. The plain one, and the one nobody notices, which is usually a compliment.

Fade through black goes out to black at the cut and back. Use it between sections that are genuinely different, not between two halves of the same explanation. It is a full stop, not a comma.

No transition on the same menu takes it off again.

Length

Short is 0.35 seconds, Medium 0.55 and Long 0.90.

Medium is the default and suits most joins. Short is right when the cut is one of many. Long is a deliberate pause and starts to feel slow if you use it more than once or twice.

The timeline does not move

Adding a transition does not push anything along, and removing one does not pull anything back. The transition happens on the boundary, using footage from either side, so a 90 second project is still 90 seconds afterwards.

This matters more than it sounds. In editors where a transition changes the length, adding one at the front of a video moves every caption, every zoom and every overlay behind it, and you find out later.

The sound crosses too

A transition crosses the audio as well as the picture, and gives the original sound back on the far side. You do not have to do anything to the audio tracks.

What it costs

Defocus is the expensive one to draw, because it is a real blur on both shots at once. On a machine with no graphics card, a project full of defocus transitions takes noticeably longer to export. Cross dissolve is nearly free.