Wouaou ! An 18 minutes video for a feature that should be built-in for 5 years now. You guys are very slow...
What I guess is that you realized that free libs will always be better than anything you could ever made. So if you wanna use them (jQuery and Co), you must autorize the developpers to set the client ID.
I don't congratulate you. You're desining your evolutions to save your plateform and not to bring innovation or to make the developper work easy.
When you dont want to allow integration of third party products, you close your API (clientID unsetable, and client id generated), but when you realize that your are 5 years late on third party libs, you allow integration to save your plateform.