Z.ai closed the weights of its own video line — then built its open animation model on a rival's

Z.ai has two video products and they point in opposite directions. CogVideoX-3, the current generation of the line the company has developed since 2024, ships no weights at all: it is sold through the API and nothing is available to download. SCAIL-2, the character animation model the company released as open weights, does not run on that line. It runs on Alibaba's. The evidence is not subtle. The download bundles Alibaba's Wan 2.1 image encoder and Google's umT5-XXL text encoder, the inference command loads a checkpoint named SCAIL-14B, and the default branch of the code repository is called wan-scail2. There is a second branch, sat-scail2, for the company's own training stack, but the weights that were actually published are the ones for the competitor's runtime. The training material came the same way. Z.ai states that 60,000 motion pairs were synthesised using three off-the-shelf models, two of them from other labs: Alibaba's Wan-Animate and Orange's MoCha. The company calls the method reverse driving and reports that the finished model acquired behaviour its teachers never had — animal-driven motion, cross-identity replacement, and control from mesh renders it was never trained on. One detail is worth checking before anyone redistributes the file. The code repository is Apache 2.0. The weights repository declares MIT in its metadata and contains no licence file at all, while the archive it hands over includes third-party components released under Apache 2.0, a licence that asks for its notices to travel with the code. The badge and the contents do not say the same thing. SCAIL-2 now has a profile in our catalogue, with the licensing situation recorded as the publisher left it.