Movie Codecs and Help..

I'm not sure I understand your problem properly, but I think you're experiencing non-smooth playback from what I understood.

It's most likely due to your madVR settings for chroma and luma upscaling being too high for you graphic card. Since madVR does it's scaling using the graphic card, it's normal that your CPU doesn't go very high, but the graphic card must be at 100%.
You can confirm the problem by pressing ctrl+j while a video is playing and checking if you have any dropped frames in the text that appears on the left(press ctrl+j again to make it disappear).
If you do have some, you need to select a less demanding algorithm. They are pretty much in order from less demanding on top to more demanding at the bottom so choose one that doesn't give you dropped frames and looks best to your eyes since they all have their strength and weaknesses so there's not really a best one(except maybe for jinc 3 taps, but that's extremely demanding so don't even think about it).
As for downscaling, I'd use catmul-rom with AR and linear light checked if your GPU(Graphical processing unit also know as your graphic card) can support it.

That guide is a bit dated so it's not up-to-date will all the new available options since madVR has had a lot of development recently.

If you're worried about the quality of the video by choosing less intensive algorithms, don't be since even the worst madVR offers is better than what the other renderer use.

There shoudn't be any difference in speed between win 7 32bit and win 7 64bit for video playback in your case since madVR is 32bit only so only 32bit application can be used. There must be something you did wrong somewhere.

I had forgotten that madVR also had the nearest neighbor option which is what most(if not all) other renderers use since it's extremely fast so it shouldn't be slower than other renderers at that point. You should even be able to use bilinear without problems unless you have a really really old computer.

The first guide you listed is pretty good except that it doesn't mention the newest additions to madVR, but it wouldn't help you to get faster video decoding. You're better off trying to understand what it ask you to install and decide for yourself what you need or what looks best.

To help you, I would need more information like what are your CPU and GPU model number(for example I have an i7-2600k for CPU and GTX 560ti for GPU) or if you don't know, what the brand and model of your computer is.
I would also need to know what is listed when you play a video, right-click the image and go in filters.

The internal subtitle renderer the guide tells you to use is much more demanding than XY-vsfilter so disabling it and installing XY would save some CPU, but from what you were saying, it didn't look like your CPU was used much so that shouldn't be a problem.

I see. That Graphic card is pretty low end so that's most likely the problem since everything else looks fine. I guess madVR is more demanding than I thought by default.

First, make sure you have the latest driver available for your graphic card since newer driver are often better optimized for speed.

Then there's a few other things you can try in madVR options to gain performance.

Make sure the anti-ringing and linear light is disabled for all 3 scaling algoriths.

In rendering, general settings, you can try to check both delay playback options and use separate device options.

In trade quality for performance, checking any of those options will help if they apply to the type of video you watch.
The 16bit buffer instead of 32bit should have the biggest effect since it applies to everything followed by the 2 10bit instead of 16bit options.

If that doesn't work and you don't watch 10bit video(mainly used for recent anime and my JAV mkv encodes), then you can try to enable DXVA2 copy-back in LAVfilters video configuration under hardware acceleration.

If you still can't get playback without dropped frames, you should forget about madVR until you upgrade your graphic card and use EVR CP(Enhenced Video Renderer (custom presenter)) as your renderer instead of madVR. It relies more on the CPU if I'm not mistaken so it shouldn't have problems with playback.

I see JanWilliem32 has made a lot of amelioration to it since I last checked and has added a lot of resizing options(which now makes my previous statement about other renderers completely untrue).
If you're using his version of MPC-HC as recommended by the first guide and video are playing properly, then I'd give Lanczos3 resizing a try(in options, playback, output) instead of Bilinear if your PC can handle it.
Another thing you can try to get better quality is right-click on the player window, Renderer Settings, Presentation and use the highest bit of surfaces your PC can handle.

You don't have to install anything for EVR CP, it comes with MPC-HC and it's what most codec pack(KLite, CCCP, etc.) use by default for a couple of years now so it was probably what you used before.

Just go in MPC-HC options, Playback, output and choose EVR CP instead of madvr.

You're still having problem using EVR with default settings?

There must be something else wrong then because your CPU should be plenty fast for most videos.

The difference between VLC and MPC-HC is that VLC only use it's own stuff and MPC-HC can use a lot of external stuff, but this means there more possibilities of problems creeping in.

Try enabling the internal filter(options, internal filters) for the type of video you're playing(I'm guessing it's Matroska or MP4/MOV for source and h264/AVC for transform if it's HD) to see if LAV filters is the problem.
You can confirm LAV isn't used anymore for the video if you right-click the image and go in filters.

If you want to figure this out faster, you could join akiba's IRC channel(link in the top menu of the site), I'm always online and I frequently check if someone's talking to me so we could try to figure it out in real time.