[theefer]

It seems you have chosen a bit of an edge case. Agreed the videos shouldn't pre-load, but to take a more standard example of a simple article:

AMP: http://tools.pingdom.com/fpt/#!/brWXpA/http://www.theguardia... Requests: 67 Load time: 485ms Page size: 627.3kB

Non-AMP: http://tools.pingdom.com/fpt/#!/eNuTPX/http://www.theguardia... Requests: 136 Load time: 2.88s Page size: 1.8MB

And to be fair, note that the non-AMP page has a lot more content, onward links, components, etc.

[Navarr]

Looking at the source - the videos aren't set to pre-load?

And don't a lot of these sources only start loading once the page has finished rendering? AMP is supposed to be fast-to-render firstmost, right?

[x1024]

It should "be optimized for mobile". 4MB per page is anything but. If you visit 100 pages per day, you'd need a 12GB data plan.

[everfree]

That assumes that you clear your browser cache after you view every page, or that you visit 100 separate sites every day that each weigh 4MB.

[x1024]

Every page weighs 4+MB, because the page-specific content on the page weighs more than 4MB. There's almost 1MB of "CSS + JS + HTML", but about 4MB of video.