These libraries need to be installed before a bottle is created in Crossover for the Windows app you want to use.
Next you need to edit the registry of the bottle you want to enable Gstreamer on, and set the registry key
[HKLM\Software\Microsoft\Windows NT\CurrentVersion\MCI Extensions] "avi"="MPEGVideo"
After that Windows applications in that bottle should be able to interface with Gstreamer to handle more multimedia formats.
We're rebels. We're misfits. But mostly, we're software liberators. And we're very, very good at what we do. We have to be. Lots of developers work with open source, but only a tiny fraction of those are good enough to get software that was designed for one platform to work on another one. We invented CrossOver software - a unique approach to cross-platform compatibility that does not require dual-boot or another OS license. We launched PortJump to help app and game developers broaden their market beyond Windows® users. And we launched ExecMode to help organizations solve really ugly technical challenges.