I'm not a big fan of how the SDL interacts with Pulse. I think running the sound through JACK would not only remove some people SDL issues, but it could let us sync with Ardour and Rosegarden. If I was smart enough to code, I'd be working on this, but I don't have the talent.
Please see about this:
Although I'm not a kdenlive or mlt developer, I'll work to make sure we got Jack support before the end of April 2010 (when Ubuntu Lucid is released)
yea it would be great to have a Jackd support, i always get crackly sound with the regula alsa set up but all my jackd sounds are nice and crisp,