From inside a discussion topic, after you click on START A THREAD button

Select on the INSERT STUFF button in the far left corner of the text box.

Select 'Add a Video Note'

Select NEW RECORDING

Allow Brightspace access to your web camera and microphone to make the recording, when prompted.

Once you have recorded your video, select NEXT

1. Title the recording

2. Add a description, if you want

3. Select the language you want the captions to use.

Then select the box next to 'Automatically generate captions from audio'

Then select NEXT and finally INSERT.