"st" is likely an abbreviation for a specific sexual act or scenario in the context of the porn video. Without more information on the full term, it's difficult to provide a clear description. However, here are some possibilities based on common abbreviations:
1. ST - Strap-on (a sex toy that mimics a penis, typically used by women during lesbian sex scenes)
2. ST - Spanking/Spitroast (a combination of anal and vaginal penetration with the same partner or different partners)
3. ST - Standing (refers to a specific position in which one or more participants are standing)
Please provide more context or the full term if you want a precise description.