Adobe has recommended screen sizes for Flash
https://www.adobe.com/devnet/flash/apps/flv_bitrate_calculator/video_sizes.html
also a bit rate calculator
https://www.adobe.com/devnet/flash/apps/flv_bitrate_calculator/
And they even include important things to think about such as talking head vs action.
They include four codec variant choices too.
Sorenson Spark (Flash 7)
On2 VP6 E and S (Flash 8 for standard and HD video)
H.264 (Flash 9)
Given that it has all the above it’s an attempt at an “intelligent” bit rate calculator that includes some proper targeting in there.