About a month ago I tried to install some filter capacitors into the video line of my A/v NES 2. All the capacitors used were .1 uF 50 v ceramics. I turned on the game and the whole screen was one giant, white streak, no game whatsoever. I figured the capacitors had weakened the signal since it doesn't have much voltage to begin with.
So I cut them out and tried smaller and smaller caps until I found something sort of interesting. I don't remember the cap size, but when I connected it, it blurred the image just barely enough to make the lines, oh, something like 20-40% less visible. It also cut down on the color bleed in the games on my TV.
What also happened was it blurred the edges of all the sprites just barely. WIth the A/V mod, colors are more vibrant and the graphics are alot sharper. Almost too sharp for the NES graphics. What this did was sort of act like anti-aliasing around the edges, and everything looked a little smoother, like it was on an emulator.
I know some of you already have experimented with the bypass capacitors, but I figured I'd just post my findings.
In theory, putting a suitable capacitor between the R/G/B signal lines and ground will slow the slewrate, hence blurring the output slightly, but only in the horizontal direction. It would be better done as part of an RGB amp, to prevent heavy loading on the output buffers though.
A low pass filter on the output is pretty severe...wouln't you be better off just using the RF output?