Can I buy a stock video with a regular license. Then use it in a WordPress theme. But only in the demo. The buyer will never receive it and its not included in the main download package.
I don’t think it’s necessary to buy it. You can just ask the author’s permission to use it in the template.
There are a lot of similar topics in the Themeforest forum.
You can just use it with the watermark,But if you insist on buying and using it in the preview,just mention the link of the Video in the Theme’s description.