So, I've been recording TATW videos at 1980 resolution for months now. I decided to crank it down to 1280x720, using the preferences configuration file in Medieval II. However, in-game it'll show the resolution at 1280x768, so there are black bars on the borders of my videos.
Here is an interesting thread by Gigantus. It deals with screen shots but may shed some light on your question. If not, you could always PM him and I am sure he would be glad to help. High Resolution Screenshots
Spoiler for Aspect Ratio from TweakGuides.com:
The ratio of the pixel width of any given resolution to its pixel height is called the Aspect Ratio. For example, the aspect ratio for a resolution of 1920x1200 is calculated first as width divided by height (1,920/1,200) = 1.6. To then express this as a proper aspect ratio, find the first integer (whole number) which, when mulitplied by this ratio, results in a whole number. The first integer which turns 1.6 into a whole number is 5. Multiply 1.6 by 5, and you have 8. Thus the aspect ratio is 8:5, which can also be expressed as 16:10. Similarly, a resolution of 1280x720 results in a width to height of roughly 1.78. The first integer which turns this into a whole number is 9, and 9 x 1.78 = 16, so the aspect ratio is 16:9. The standard aspect ratio for traditional computer monitors and televisions used to be 4:3 or 5:4, while the standard aspect ratio for the current widescreen TV and PC monitor format is 16:9 or 16:10. Resolutions which precisely match the aspect ratio of your monitor will display correctly, while those that do not have the same aspect ratio will either result in distortions to the image, or black bars to the sides and/or top and bottom of the screen.
Almost all LCD monitors now being sold are classed as 'widescreen', as the traditional 4:3 monitors have been phased out. But in actuality there are two different widescreen aspect ratios for computer monitors: 16:9 and 16:10. Up till now, the separation has been reasonably clear: 16:9 is considered a movie aspect ratio, used for displays primarily intended for TV/movie playback such as Plasma and LCD TVs. The 16:10 ratio on the other hand is considered a PC-exclusive aspect ratio, and has been used almost solely for LCD computer monitors. In recent times however, more and more computer monitors are being released as 16:9. This isn't necessarily due to more people using their computer monitors for watching movies, it's actually because the hardware manufacturers find the production of 16:9 panels to be more cost efficient for them, as pointed out in this article. What this means is that 16:10 LCD monitors are being deliberately phased out in favor of 16:9.
The 16:10 aspect ratio was a compromise designed specifically for PCs to allow them more vertical room than a 16:9 monitor. Browsing the Internet for example usually benefits from more height than width, as web pages are not designed to efficiently use horizontal space, and more height means less scrolling to read text. The same is true for word processing, since the standard page formats of A4 and Letter have much more height than width. Yet when a 16:9 image is displayed on a 16:10 monitor, there isn't any major issue; while maintaining native resolution, small black bars are simply added to the top and bottom of the screen, without any major loss in image size. However a 16:9 monitor cannot easily accommodate a 16:10 image for obvious reasons, and thus must step down a resolution or two to show the image in its entirety, adding black bars to the sides in the process. In short, at the same screen size, a 16:10 monitor provides more screen real estate. For those who use their PCs for normal desktop tasks such as browsing and writing emails and documents, 16:10 is therefore a better choice at most screen sizes. However if you still prefer a 16:9 monitor, or only have the choice of a 16:9 monitor, then it doesn't make a substantial difference because manufacturers are pushing consumers towards 16:9 and hence support for 16:9 resolutions will only continue to improve as it is the standard.
Importantly, there are various scaling options available in your graphics card control panel and/or monitor options which control how an image is displayed if it does not match aspect ratio of your monitor. The details are provided under 'Adjust Desktop Size and Position' section on this page of my Nvidia Forceware Tweak Guide, and on this page of my ATI Catalyst Tweak Guide under 'Digital Panel Properties'. You can both increase image quality by forcing your graphics card to rescale an image before sending it to your monitor, and also fix any aspect ratio-related problems - such as a 'squished' image - using these settings.
I did send him a message and I'm hoping he may have a solution. When I play at a lesser resolution, I can turn everything up even when having multiple thousands on the screen. That would be a nice change of pace, instead of having lower settings with my rig when using fraps.
I hope he can help you, I really enjoy your videos!
Updated my previous post, just some interesting background information you may already be aware of.
Someone else who may be able to help would be MasterBigAb, he makes quite a few videos for Total War mods as I am sure that you are aware.
Edit: Actually watched the video in your fist post and the black bars are not really that bothersome. If I had to make a choice between more detail with bars or less details without the bars I would prefer the former.
Edit 2: I know that you said that you changed your resolution in your cfg file, but here is a thread with a title almost like yours. Is 1280x720 possible?
Gigantus actually just responded and it seems the sole solution is to apply those commands to the configuration file. It may just be that Medieval II doesn't support that resolution, which is very weird to me.
I would honestly stick to the higher detail despite the black bars, but it feels entirely unprofessional to me. Ah well, I'll have Gondor episode 5 up in a bit on a side note. Episode 6 will revert back to 1980x1080 resolution again. Ah well, it was worth a shot!