That was a great video, thanks! Organizing and routing cables isn't rocket science, but I watched this vid and it got me going.
I have an Antec 900 and this is my first build. When I originally built it about a year ago, the cables were just godawful. A few days later I rebuilt it because I installed a zalman 9500 and I also made an attempt at cable management. This is what you see in the before shot.
Today I basically just stripped it down and tried to route stuff nicer. I moved the hdd's down and turned them backwards to hide their cables (neat trick). The 900 is really nice, but it can get cramped when you're trying to wire it. I didn't want to dremel any holes to get wires behind the mobo tray because that would require removing everything, but I did drill a few as anchor points for zip ties. You can't see it too well in the after shot, but all of those cables btwn the mobo and hdd cages are flat against the case. That in itself is a big improvement. A few people here just cut off the psu cables they don't use, but I didn't think they were doing any harm at the bottom of the case (p.s. you save them and solder them back on if you need them
The only minor difference I saw in temps was the cpu... maybe 1-2 degrees cooler. But it's a lot nicer to look at now, lol. I don't think I did too badly.
Cable management is definitely a bit harder when you have a bottom-mount PSU. ATX was just designed to have the PSU at the top where all the power connections are.