I think the only interface for animation now is Motion Studies, i.e. the API docs for the regular SW animation feature say:
Animation Object
This interface is:
obsolete and has not been superseded.
nonfunctional in SolidWorks 2008 and later.
Use the interfaces related to motion studies introduced in SolidWorks 2008 to access animation and simulation.
This doesn't appear to be too useful though, since the only types of commands available in motion studies appear to be start/stop kinds of things - basically just exposing control to those buttons in the UI. But then, I think it was no different with the older animation APIs. I've thought, it might be possible to create a hack, where you would start and then stop the motion study every
n-milliseconds and export an .mxs using the plugin's scripting object from VBA. At this point, something like that looks to be the only option - there are (afaik) no API events or callbacks that a plugin (or a macro) can listen to in order to tell when the frame is being advanced.
JD