Well, since Haiku *shoud be* THE multimedia OS, i think that a killer application is needed (that may bring many users/manufacturers), so here's my port suggestions:
1. HyperEngine-AV, Arboretum Systems' award winning video editing software is now free, complete with full source code. Users can capture, arrange, edit and process video, audio and text in a free-form, trackless document, to create movies and slide shows. OSX, GPL

2. Cinelerra, a non-linear video editor that does primarily 3 main things: capturing, compositing, and editing audio and video with sample level accuracy. (Linux, GPL)