Can't say I've seen that. I've never been in a home where people did that. I've certainly seen two groups of people watching different TVs, but never everyone off watching their own show.
Also I have a little trouble believing that everyone is going to be watching high bitrate HD video all off of your fileserver at the same time. Particularly when you start talking wireless devices like tablets, which don't have that kind of bandwidth. N has 150-200ish mbps max effective throughput (it has a lot of overhead with respect to the raw rate) at its best, and it is shared among all devices on an AP.
So you are trying to tell me that you have enough people in your house that, at one time, access enough resources on one server to hammer a gig NIC? Sorry, having a little trouble buying it. Particularly since if you don't have an SSD, 15k SAS RAID, or really high performance NL-SAS array in said server, the disk would be the limit. You'd be asking magnetic media to do heavy random access since it would be streaming multiple different files and that is what magnetic media falls down on the hardest.
So if your scenario is truly something you do, and not just someone making up a make-believe scenario to somehow justify why a home would need 5 figures worth of networking hardware, then here's what you need to do:
1) Look at compressing your videos more. If you've ever watched 1080p on Youtube it isn't bad. So, for many things, knock the bitrate down to 6-10mbps. That'll get you decent video and plenty of overhead.
2) Get everything on to SSDs on your server. Yes, that will be a lot more expensive. However magnetic disks can't hold up to that kind of load without going to an enterprise type array and that is likely to be even more expensive. The Crucial m5 is a good not too expensive choice. 960GB for $600ish. That has both the IO performance and iops to handle high bandwidth random access.
3) If that still hasn't fixed it, and I expect it will, get a dual port server NIC. the Intel i350 is a great choice. You want one that does offload and bonding. If you want more, get a 4 port, they aren't a lot more.
4) Get a managed switch. Doesn't have to be a high end one, just one that can do LACP/LAG. Then, bond the gigabit NIC ports together and same on the switch. Presto, you've got 2 (or 4) gbps out to your devices.
Do note this won't fix WiFi contention if that's the issue. There isn't anything you can realistically do to increase that bandwidth that isn't an administrative and implementation nightmare, so you'll just have to wait for 802.11ac on new versions.
As I said, NIC bonding fixes this issue much cheaper. I mean let's say you had 6 devices, each streaming a solid 50mbps. That'd kill a gig port and then some. Ok so right now if you got the cheapest 10 gig NICs and switch on Newegg you'd be out about $3000 and the switch is rated as being crap and you still get to buy the Cat-6a cable. On the other hand if you bought a 4 port gig NIC and a cheap web managed gig switch, you'd be out about $450 and could use your existing Cat-5e cable. In either case, you'd get the bandwidth to meet your rather high end needs. You could do it for literally about 10% of the price (particularly once you factor in Cat-6a cable) and not have a jet-engine sounding switch (which the cheapish 10gig Netgear apparently is).
Seriously man, stop trying to justify new tech for its own sake. It is the kind of thing to get when there's a reason, not try and figure out a way as to why everyone should get it RIGHT NAO!