Generate how-to videos to replace the ones we have currently (which are muted)

[oesteban]

We have two movies at https://mriqc.readthedocs.io/en/latest/reports.html, but they don't have sound.

It has been discussed #771 that it would be helpful for everyone to generate similar movies with up-to-date reports AND sound.

We're hunting volunteers who would like to record themselves in one or more such videos.