I think I can answer this question.
Not every key you want will simply be given.
Companies want to make money. They will review your youtube account (or other medium) and if they think that you have a large enough amount of followers, they might send you a key.
This website does not give away keys for charity, but if developers think giving you a free key and get you to create a video that generates 10 buyers, then they will give you a key.