Many video producers will keep secret of their video resources because that is where they make their dollars. Ok, who wouldn't? That's how to remain relevant in the market. Now, note that without regular research and updates- these resources will become obsolete someday. Market and trends change. This means that video producers who relied on these resources will loose their market value.
Considering that it may take you 1 day to find a suitable freelancer to take over the project, having them understand the presentation style, idea and so forth will take you another 1-2 days. He/she will have to send you their version then you review it before sending it to the client.
It's no doubt, online courses are on high demand at moment. But the fact is still remains, 80% of the total income generated from online courses are earned by top 20% percent course creators.