I open my hikvision cam with Internet Explorer, for the live view.
Is there a way to create a shortcut in windows, so the user and password is automatically entered on the login page? (It can be in the link in plain text)
Maybe it's your cam; have you logged in to see if user or stream has a duration limit setting?
I've viewed my Amcrest (rebranded Dahua) IP2M-721 for >24 hours at least on VLC with no issues. And this cam can stream RTSP to VLC with user/pass in the URL (below) or you can config cam via it's webGUI to allow non-admin users or even an anonymous login to it's webGUI using IE11 with NO user/pass.