Windows Media Player 12 cannot play Cartoon Animator MOV videos without the prior installation of the K-Lite codec pack.

You can download and install the free basic version of the K-Lite codec pack from this link:
https://codecguide.com/download_k-lite_codec_pack_basic.htm

Note:
- MOV video files exported with transparency will not retain its transparency when imported back into Cartoon Animator.
- To keep transparency, use the PopVideo option to render videos