Webconferencing that supports audio/video/multimedia?

I work for a music and sound design agency. One of the nice benefits of AdobeConnect web conferencing is that we can share Powerpoint presentations that contain a lot of video, sound or music files with meeting participants virtually, but still maintain control -- on the presenter's side -- of when/if multimedia gets played for participants. This kind of control is especially important in pitches and client presentations when one doesn't want the participants racing ahead to see the big payoff slide.

The problem is that loading and cueing these types of files is a bit tedious in Adobe Connect; we usually need to have one person presenting, and another person getting the multimedia files cued to play. It seems like most of the other major web conferencing services, like WebEx etc. don't support PRESENTER-DRIVEN control multimedia in this specific way. Can anyone recommend alternative services out there that have this kind of multimedia control, but are more intuitive and seamless to use?