NOTE:
larger data rate (bit rate), fatter file (more data/sec), better quality the file.
more keyframes (lower keyframe distance), fatter file, better quality file.

//////

MP4 (USUALLY) OPTIMAL

wih Adobe Media Encoder:

H.264

(can choose from preset dropdown to get an idea)

preset: custom:

video >> bitrate settings >> bitrate encoding >> 
CBR (constant bit rate)
Target bitrate [Mbps]: 2.6
advanced settings >> leave keyframe distance unchecked

multiplexer >> mp4
stream compatibility >> standard

at bottom, it will show you estimated file size

--

audio
AAC
audio quality: high
sampe rate rate 44.1
bitrate 128 kb/ps

//////////////////////

MP4 THINNER

wih Adobe Media Encoder:

H.264

(can choose from preset dropdown to get an idea)

preset: custom:

video >> bitrate settings >> bitrate encoding >> 
CBR (constant bit rate)
Target bitrate [Mbps]: 1.372
advanced settings >> check key frame distance: 150

multiplexer >> mp4
stream compatibility >> standard

at bottom, it will show you estimated file size

--

audio
AAC
audio quality: high
sampe rate rate 44.1
bitrate 128 kb/ps

//////////////////////

FOR OGV. Use Firefogg:

begin with hi-res .mov or .mp4 if you have it. Otherwise, just convert your web-ready .mp4s.

short cuts (just eyeball them afterwards and check file size):
1080p (optimum). or do 720p (better) or 420p (passable).

If all those look to crappy, do "custom" and apply above mp4 settings, two pass encoding, de-interlace, audio quality 4 (this is equivalent to 128 data rate), video quality 3-5.

If it really gets crazy (too fat, too low res), just start with the web-ready mp4 that you have >> try the short cuts >> then try custom, etc.