I understand why @YouTube has the "set reminder" for live streams, but I'm seeing it for regular posts as well. Why? Isn't that what the f'n bell is for, to let me know when something new is posted.
Check your bell settings for that channel and see if you've opted-in to receive all notifications? You may be on the default setting, which is to receive notifications occasionally. Here's a guide to help check that plus your app and device level settings: https://goo.gl/giVA8o