Looking at the internet there are videos like https://youtu.be/EA9bFOmcWfc or https://www.ouest-france.fr/bretagne/rennes-35000/video-aidez-mozilla-creer-la-reconnaissance-vocale-en-breton-6101688 but if people very skilled with video editing can do a video about:
- Why contribute
- How works Common Voice
And give space for localization (audio and written) and other custom stuff by the community itself or the language (like links of a social network or a page) can help in the promotion.
In Mozilla Italia we tried to do a video, but we don’t have any resource to do the video. We have about the audio anyway, so we can customize the video based on our needs.