Isn’t it possible to export the pure mesh animation so that you can delete the rig? Blender 2.9 can read the formats “Alembic” (.abc) with the “Mesh Sequence Cache Modifier” (see here) and MDD and PC2 with the “Mesh Cache Modifier” (see here). Blender 2.66 only had the “Mesh Cache Modifier”. Unfortunately I’m not experienced with these formats and don’t know how “Sheepit” mentioned above by @rodri handles this.
However, there’s an Addon already in Blender 2.66 for exporting animations to MDD:

@stanp (see here on CG Cookie Stan Paillereau) describes it in his “Book Rigging” tutorial (I don’t know anymore in which of the 4 parts; see first part here) but as far as I can remember he had some problems with the orientation when reimporting it into Blender. See also https://cgcookie.com/u/stanp/projects/book-rig .