Some of the video filters include: Add noise, color curves, deinterlace, denoise (hqdn3d), deshake, draw box, draw grid, fade in, flip horizontal, flip vertical, gamma, geq - emboss, grayscale, histogram, hue and saturation, mplayer: gamma, brightness, contrast (experimental), negate, pp - deblocking, deringing, auto brightness & contrast, sepia, smartblur, unsharp, vignette, and YUV420P.
The VF cheat sheet is by no means a substitute for ffmpeg's documentation --- so, if the default values do not satisfy you, read the ffmpeg manual.
Here are some screen shots...
'play both (horizontal)':
|filters used: gamma, curves, saturation, unsharp, denoise, deblock, yuv420p|
'play both (vertical)':
And finally, 'play both @ pos 0x0': Both source and processed windows are placed on the top left corner (one window obscures the other). Clicking 'toggle' alternates between the source and processed windows. This lets you easily see the differences, especially small differences, between the processed and the source windows.
VidProk is included in 'VidProkEnMasse', it is absolutely free, and you can download it here: