This document provides answers to the questions outlined in Section 2:
 
   o  How often is feedback needed?
   o  How much overhead is acceptable?
   o  How much, and what, data does each report contain?

The answers to these questions are well reasoned, and are useful to document, as is the conclusion: 

"  If it is desired to use RTCP in something close to its current form
   for congestion feedback in WebRTC, the multimedia congestion control
   algorithm needs to be designed to work with feedback sent every few
   frames, since that fits within the limitations of RTCP.  The provided
   feedback will be more detailed than just an acknowledgement, however,
   and will provide a loss bitmap, relative arrival time, and received
   ECN marks, for each packet sent."

It occurs to me that the gist of this paragraph might be worth including in the Abstract and/or Introduction, so as not to "bury the lead".  

Also, it might be worth noting that the improved compression of recent codecs such as AV1 and VVC implies that the rate required for high quality video has been substantially reduced, which exacerbates the overhead issue.