I hate this so much! I clicked the link because I wanted to see what was on the other side! I know I'm leaving YouTube, and if you want me to stay so that I spend more time on your shitty platform, just make it target="_blank".

Oh no! Please no target blank! I want to decide myself if I want to open a new tab. I have the same feelings though

@coolboole there are 2 reasons why YouTube would do this:
1. Prevent people clicking dodgy links
2. Retainment of users

(I wrote too much below. TL;DR I don't think that would make sense. 2 is more reasonable. (Or maybe I'm just overly cynical))

In the case of 1, YouTube would scan the URL. You can tell they're not doing this, because of you click a goo.gl link that redirects back to YouTube is still warned and it even warns for google.com links. This doesn't make sense to me. Anyway it would be redundant because modern browsers and OSes have some malware detection built in. If YouTube were to scan the links and warn for only those, it would be equivalent to the browser protection. Or exactly the same, for Google Chrome (they'd both use Google Safe Browsing). There would also be a way to turn this off.
This leaves option 2 only.