In practice, how much different is Apple 2x Blueberry x vs just Apple in? Blueberry is 'represented' but its vote gets dwarfed by Apple. If our society were just this district, then it wouldn't be any different than just electing Apple alone (except for the extent to which Blueberry and Apple can influence each other while working in the same building, or whaterver).* So we actually have lots of these, so you have an aggregate effect, though it's not clear to me how that plays out in practice.
It's a lot different! Our society is not just this district (and if it were, you could divide up that district so that it wasn't); the difference between a president and a parliament. And Apples aren't 100% party-line.
It is still a problem that then when the elected people themselves vote, they are using traditional awful voting. I have various approaches there, as you know from the video. The only perfect thing I have though is this method for voting on voters. In this one case you can just perfectly make each vote mean something, as much as it ever could, in a way that's very easy to understand.
In general it's ideal to replace voting with "choosing" as much as possible, everywhere that voting is used. The key concept of voting is "compare totals" and that just automatically throws away information about what people wanted. So in general my solution for "Congress votes on things" is to try to convert those votes to choices; for example instead of "vote on a budget" there's "each member gets a proportional amount of the budget to decide." That one example immediately doesn't work; everyone games the system, "you can put your money on roads like a chump, mine is 100% going to this thing only my party likes, oops no-one funded roads." But then you can work on, is there a way to fix that. In some cases there will be.
Obv. this innocent mathematical discussion should go to RSP, as people will helplessly bring in tangential issues.