Can you give an example of a ustream channel that uses HTTP dynamic streaming? Some ustream channels I've tried are still working and recording fine!!!
Code:
rtmpdump -r "rtmp://flash87.abvt.tcdn.ustream.tv:1935/ustreamCdn/flash10/14067349" -a "ustreamCdn/flash10/14067349" -f "WIN 11,9,900,117" -W "http://static-cdn1.ustream.tv/swf/live/viewer.rsl:572.swf" -p "http://www.ustream.tv/explore/news" -y "streams/live_1" --live -o "ariangnewslive.flv"
EDIT: Someone sent a ustream link that appears to fit your description above. I can play it on VLC just fine, but I cannot record it

(non-rtmp).
KSV would have to decide if he want to add it to his HDS Downloader script, or not

Cheers!