I added a table below the map that contains some additional information. It isn't very intuitive and it's hard to describe in the short column headings in the table (I'm open to suggestions) but I'll leave a couple of notes here and add some explanation to the production page later.

In the table, I have totals for each of the counties involved in the selected commuter flows. This includes a "median" commuting distance for commuters who live in the county and a median commuting distance for commuters who work in the county.

In addition at the right side of the table, there are a couple of percentages:

the "% This County" shows the % of that county's residents are part of the main selected county's workers (if "workplace" is the selected view) or the % of that county's workers who are part of the main selected county's residents (if "residence" is the selected view.)
the % Selected County shows the % of the selected commuters who live/work in this county (depending on the selected view), so these should add to 100%.

The median distances are calculated using the same number that drives the distance range criteria: the distance between the center of each census tract. Thus, intra-tract commutes count as 0. By sorting the tracts by distance, I found the tract-tract flow that contained the median commuter (if 1,000 commuters, the 500th commuter) and used that flow distance as the median.

Anyway, if nothing else the totals on the left side of the table will show you what I have as the total workers/residents in my tables.

Thanks and let me know if any suggestions or questions,

Mark