[rtmpdump] Frames lost

[Etiam]

Hi,

I recently tried to download some video lectures using rtmpdump but it 
seems that most of the picture frames are consistently lost. 
(Interestingly enough, the first 70 seconds or so seem perfectly normal.)
https://www.ipam.ucla.edu/wowzavideo.aspx?vfn=10660.mp4&vfd=gss2012 is 
one the videos.
I have been asking in the fora at stream-recorder.com and videohelp.com, 
but no-one has been able to offer any explanation to why the problem 
occurs, or any way to fix it.
I hope asking here is appropriate.
I have described the problem and posted some additional information at

http://stream-recorder.com/forum/picture-freezes-slideshow-like-file-downloaded-wowza-t16265.html

I don't have any previous experience of needing to modify the output 
from rtmpsrv and may well be missing some intricacies of rtmpdump, but 
I'm beginning to suspect this may be material for a bug report or 
feature request. Please tell me if you need more information.