3-5 minutes is optimum, no longer than 10 minutes when possible.
If you must use a longer video, break it up into smaller, stand-alone chunks.
Writing
Write a script or at least an outline.
Write in as conversational and as friendly a tone as you can.
Use short sentences.
Write for the ear – not for the eye (most people will only hear the video narration so you can be informal, use contractions, etc.).
Read your script out loud (then you'll hear where you need to make changes).
Recording
Rehearse and practice before you press the "Record" button.
When using a camera, do a test recording to make sure you are comfortable with all the controls.
If you make a mistake or stumble over words, let the recording continue, pause for five seconds, then pick up again where you left off. You can edit out the bad portions later.
Captioning
You should either caption your video or offer a text transcript of the audio.
You can embed the hosted videos so students will view them in your course.
You can link to the videos from a course.
Copyright Considerations: Be sure you have the right to use any videos that you want to add to your courses. If you're unclear about what those rights are and what your responsibilities include, please review these resources: