On 'network neutrality', I'm lost: Someone please clear this up for me, say, with this 'scenario': I pay my ISP for 15 Mbps download bandwidth, and some Web s

On 'network neutrality', I'm lost: Someone please clear this up for me, say, with this 'scenario': I pay my ISP for 15 Mbps download bandwidth, and some Web site with video clips pays their ISP for 10 Gbps upload bandwidth. So, I connect to that Web site and download or 'stream' a video clip. Then the Web site better get their 1 Gbps upload bandwidth, if they want to send that much, and if they send me 15 Mbps of video then I better get the full 15 Mbps I paid for. So, what's the role of 'fast lane', 'slow lane', the Web site paying my ISP for 'more', 'slow downs', etc. Or as far as I can see, if I'm getting my 15 Mbps (from any Web site sending me that much) and the Web site is getting their 1 Gbps, everything should be okay. Otherwise, either my ISP or the Web site's ISP is not delivering what they were paid for, and I have a tough time believing that that would be common. I'm failing to see the opportunity for funny business. Or, yes, if use the Internet as a video phone, then there could be issues of dropped packets, out of order packets, latency, jitter, etc. -- is that what the talk is about?