YouTube, Netflix, music streaming, most video conferencing, and general web browsing all work fine on a 1.5Mb/s link in my experience. It's certainly not fast, but it's fast enough to do the basics.
Most things you mention are a matter of buffering and waiting it out, so those will work in a 'basic' fashion as you say. But video conferencing? Even in a 1:1 call, where you need to download only one audio and video stream, if you don't live alone (most people don't), I would be very impressed if you got a router that can recognise and prioritise the call traffic to the point where that works smoothly.
I used to have 768kbps down / 128kbps up cable internet. There was some buffering on Netflix at the start of a stream but it was fine. When we got upgraded to 1.5Mbps down / 256kbps up there was basically no buffering at the start of Netflix or YouTube streams and FaceTime worked fine.
