We Ran HeyGen Video and Vidu Q4 Through Our Detector on Launch Day

A Formula 1 car crosses the frame in under a second. For the rest of the clip the camera holds on an empty, blurred track. Nothing else happens.

The clip is one of the samples HeyGen published for its new model, HeyGen Video. Our detector looked at it and leaned towards real. It was one of two HeyGen samples it missed.

HeyGen is best known for AI presenters who read a script to camera. HeyGen Video is a general model that generates whole scenes. About a week after it came out, the Chinese company Shengshu released Vidu Q4 Preview, a new version of its Vidu model. Our detector had seen neither during training, so we checked both as soon as clips were available.

We used clips the companies and early users posted themselves: 40 samples from HeyGen's launch page and 12 Vidu Q4 clips, including Vidu's official promo, posts by testers on X and videos from Vidu's website. These files are close to what the generators produced. Videos that have been reposted and recompressed are harder to check, so results on other copies may differ.

The detector put 38 of the 40 HeyGen clips and all 12 Vidu clips on the AI side. Its guess at which model made them was mostly wrong.

Why the race clip got through

Our detector checks the picture and the sound separately and then combines the two results.

In the race clip the picture gave it almost nothing to work with: one second of a car, then an empty, blurred background. The sound model was close to certain the audio was generated. When the two disagree, the detector gives more weight to the picture, and here that tipped the verdict towards real.

The weighting is deliberate. Many real videos carry dubbed voices or music added in editing, and a detector that trusted sound more would flag them as fake. The price is that a clip like this one, with a convincing picture and a generated soundtrack, can slip through.

The other HeyGen clip we missed had the same problem: a line of words painted on a wall, holding still for five seconds.

Vidu Q4: caught by the picture

With Vidu the picture did the work. It flagged all 12 clips with high confidence. The sound helped much less. On Vidu's official promo, which has a narrator, the sound model found almost no sign of generation.

On half of the Vidu clips the sound alone would not have been enough to call them generated. Across the two models, the picture caught what the sound missed and the other way around.

The generator guess was wrong

Under the verdict, our detector shows a guess at which model made a clip when it is confident enough. On these two launches the guess was wrong almost every time it appeared.

On HeyGen's samples it most often named Google's Veo. According to HeyGen's documentation, HeyGen Video is built on MiniMax H3, an open-weights model, and trained further in house. On Vidu Q4 the guess appeared on two of the 12 clips. It said Kling once and Veo once.

The guess works from style: how a model lights a scene, moves the camera and renders skin. A model it has not seen before, or an open model a company has retrained on its own footage, has a style it does not know. It then names the closest one it does know.

Detecting that a clip was generated relies on other traces, and those held up on both launches. Naming the model will get harder as more companies build on open models, so we read any "made with" label, including ours, as a hint.

If you are checking a clip yourself

• A "real" verdict on a still or nearly empty shot is weaker evidence than the same verdict on a busy scene. Clips with little movement are hard for every detector.
• Listen with headphones. Generated sound is often too clean for the place it claims to come from.
• Look for where the clip first appeared. Brand videos and news footage usually exist somewhere official; generated clips often exist only in the post you are looking at.
• If you can, get the original file. Each repost and screen recording strips out detail a detector could use.

If a clip in front of you might have come from HeyGen Video, Vidu or another generator, you can check it with our detector by uploading the file or pasting a link.

More on specific generators: Veo 3, Sora.