I understand that they want to charge $99 per month to embed photos since you could argue they need to pay for hosting but there are no instructions on how or if it's possible to download the full database of 100M geotagged photos, except for a "Contact Us" on their pricing page if you want "access to Mapilliary data".
Crowdsourcing photos by getting people to contribute with a headline "street level photos for everyone" and then charging for access seems like a hustle.
If the database is publicly available for computer vision research, please provide a link and make it more explicit!