I never used rtmpdumphelper, but from what i understand it records every stream it finds. Also you have to keep the stream running in your browser.
My userscript integrates in the streaming site, so you can choose which stream to record and get a feedback if you are allready recording this stream.
The userscripts are fetching the rtmpdump options, so one could open the page, start the recrording and leave the page. (No auto record this way, though)
I added an auto record feature (still pretty alpha) which means:
Go to the page, hit auto record and leave the page open. Every time the stream goes online, the script starts to record the stream.
Also open source
The only problem i see with this is the websites
could detect the injected code (which could be hindered by the userscript though)
So, if you only want to record one stream rtmpdumphelper might be more comfortable (when it comes to the installing part). If you wan't to record specific streams my tool might be more comfortable.
Anyway, i'll install rtmpdump and see what it can do.