Designed to mimic a "cloud-like" movement as the wearer walks.
The "[491]" in the filename most likely designates a or a specific client order ID used by the boutique or videographer to track the fitting. These videos are commonly used for: Tiffany Angel Dress [491] mp4
A record for the designer or seamstress to document the custom modifications made to the standard "Angel" template for a specific client. Designed to mimic a "cloud-like" movement as the