With this product-specific custom field you store a description text for the "Product videos" on the product page. The input field is HTML-capable.
Note: You can enable/disable the "Product videos" in the theme configuration.
Custom field
You can find the "Product videos (Text)" custom field in the respective product:
Tab "Specifications" ⇒ Block "Custom fields" ⇒ Tab (Set) "Videos (... Pro)"
Type: Text editor (HTML)
Technical name: twt_{theme}_{edition}_custom_field__product__videos_text